iOS日常小问题收集

1、去除数组中重复的对象

NSArray *newArr = [oldArr valueForKeyPath:@“@distinctUnionOfObjects.self"];

2、编译的时候遇到 no such file or directory: ／users／apple／XXX

是因为编译的时候，在此路径下找不到这个文件，解决这个问题，首先是是要检查缺少的文件是不是在工程中，如果不在工程中，需要从本地拖进去，如果发现已经存在工程中了，或者拖进去还是报错，这时候需要去build phases中搜索这个文件，这时候很可能会搜出现两个相同的文件，这时候，有一个路径是正确的，删除另外一个即可。如果删除了还是不行，需要把两个都删掉，然后重新往工程里拖进这个文件即可

build phases

3、iOS8中实现侧滑功能的时候这个方法必须实现，要不然在iOS8中无法侧滑

// 必须写的方法，和editActionsForRowAtIndexPath配对使用，里面什么不写也行

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

}

4、SDWebImage本地缓存有时候会害人。如果之前缓存过一张图片，即使下次服务器换了这张图片，但是图片url没换，用sdwebimage下载下来的还是以前那张,所以遇到这种问题，不要先去怼服务器，清空下缓存再试就好了。

或者更换SDWebImage本地缓存

[[SDWebImageManager sharedManager].imageCache storeImage:image forKey:imageStr toDisk:YES completion:nil];

5、上线前注意：

1）、删掉代码中所有的测试代码

2）、如果后台有审核模式，提醒后台开启此模式

3）、主流程再跑一跑

4）、全局搜索waring，检查所有标记waring的地方

6、跳进app权限设置

// 跳进app设置

if (UIApplicationOpenSettingsURLString != NULL) {

UIApplication *application = [UIApplication sharedApplication];

NSURL *URL = [NSURL URLWithString:UIApplicationOpenSettingsURLString];

if ([application respondsToSelector:@selector(openURL:options:completionHandler:)]) {

[application openURL:URL options:@{}

completionHandler:nil];

} else {

[application openURL:URL];

}

7、给一个view截图

UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0.0);

[view.layer renderInContext:UIGraphicsGetCurrentContext()];

UIImage *img = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

8、开发中如果要动态修改tableView的tableHeaderView或者tableFooterView的高度，需要给tableView重新设置，而不是直接更改高度。正确的做法是重新设置一下tableView.tableFooterView = 更改过高度的view。为什么？其实在iOS8以上直接改高度是没有问题的，在iOS8中出现了contentSize不准确的问题，这是解决办法。

9、注意对象为nil的时候，调用此对象分类的方法不会执行

10、collectionView的内容小于其宽高的时候是不能滚动的，设置可以滚动：

collectionView.alwaysBounceHorizontal = YES;

collectionView.alwaysBounceVertical = YES;

11、设置navigationBar上的title颜色和大小

[self.navigationController.navigationBar setTitleTextAttributes:@{NSForegroundColorAttributeName : [UIColor youColor], NSFontAttributeName : [UIFont systemFontOfSize:15]}]

12、颜色转图片

+ (UIImage *)cl_imageWithColor:(UIColor *)color {

CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);

UIGraphicsBeginImageContext(rect.size);

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetFillColorWithColor(context, [color CGColor]);

CGContextFillRect(context, rect);

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return image;

}

13、强／弱引用

#define WeakSelf(type) __weak typeof(type) weak##type = type; // weak

#define StrongSelf(type) __strong typeof(type) type = weak##type; // strong

14、由角度转换弧度

#define DegreesToRadian(x) (M_PI * (x) / 180.0)

15、由弧度转换角度

#define RadianToDegrees(radian) (radian*180.0)/(M_PI)

16、获取图片资源

#define GetImage(imageName) [UIImage imageNamed:[NSString stringWithFormat:@"%@",imageName]]

17、获取temp

#define PathTemp NSTemporaryDirectory()

18、获取沙盒 Document

#define PathDocument [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]

19、获取沙盒 Cache

#define PathCache [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject]

20、GCD代码只执行一次

#define kDISPATCH_ONCE_BLOCK(onceBlock) static dispatch_once_t onceToken; dispatch_once(&onceToken, onceBlock);

21、自定义NSLog

#ifdef DEBUG

#define NSLog(fmt, ...) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__)

#else

#define NSLog(...)

#endif

22、在主线程上运行

#define kDISPATCH_MAIN_THREAD(mainQueueBlock) dispatch_async(dispatch_get_main_queue(), mainQueueBlock);

23、开启异步线程

#define kDISPATCH_GLOBAL_QUEUE_DEFAULT(globalQueueBlock) dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), globalQueueBlocl);

24、通知

#define NOTIF_ADD(n, f) [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(f) name:n object:nil]

#define NOTIF_POST(n, o) [[NSNotificationCenter defaultCenter] postNotificationName:n object:o]

#define NOTIF_REMV() [[NSNotificationCenter defaultCenter] removeObserver:self]

25、修改textField的placeholder的字体颜色、大小

[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];

[textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

26、统一收起键盘

[self.view endEditing:YES];

[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

27、控制屏幕旋转，在控制器中写

/** 是否支持自动转屏 */

- (BOOL)shouldAutorotate {

return YES;

}

/** 支持哪些屏幕方向 */

- (UIInterfaceOrientationMask)supportedInterfaceOrientations {

return UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight;

}

/** 默认的屏幕方向（当前ViewController必须是通过模态出来的UIViewController（模态带导航的无效）方式展现出来的，才会调用这个方法） */

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {

return UIInterfaceOrientationLandscapeLeft | UIInterfaceOrientationLandscapeRight;

}

28、获取app缓存大小

- (CGFloat)getCachSize {

NSUInteger imageCacheSize = [[SDImageCache sharedImageCache] getSize];

//获取自定义缓存大小

//用枚举器遍历一个文件夹的内容

//1.获取文件夹枚举器

NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];

NSDirectoryEnumerator *enumerator = [[NSFileManager defaultManager] enumeratorAtPath:myCachePath];

__block NSUInteger count = 0;

//2.遍历

for (NSString *fileName in enumerator) {

NSString *path = [myCachePath stringByAppendingPathComponent:fileName];

NSDictionary *fileDict = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];

count += fileDict.fileSize;//自定义所有缓存大小

}

// 得到是字节转化为M

CGFloat totalSize = ((CGFloat)imageCacheSize+count)/1024/1024;

return totalSize;

}

29、清理app缓存

- (void)handleClearView {

//删除两部分

//1.删除 sd 图片缓存

//先清除内存中的图片缓存

[[SDImageCache sharedImageCache] clearMemory];

//清除磁盘的缓存

[[SDImageCache sharedImageCache] clearDisk];

//2.删除自己缓存

NSString *myCachePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches"];

[[NSFileManager defaultManager] removeItemAtPath:myCachePath error:nil];

}

30、模型转字典

static NSSet *classes;

- (NSMutableDictionary *)getParameterDictionary {

NSMutableDictionary *dict = [NSMutableDictionary dictionary];

Class c = self.class;

while (c) {

unsigned count;

objc_property_t *properties = class_copyPropertyList([c class], &count);

for (int i = 0; i < count; i++) {

NSString *key = [NSString stringWithUTF8String:property_getName(properties[i])];

dict[key] = [self valueForKey:key];

}

free(properties);

// 获得父类

c = class_getSuperclass(c);

if ([self isClassFromFoundation:c]) break;

}

return dict;

}

- (BOOL)isClassFromFoundation:(Class)c

{

if (c == [NSObject class] || c == [NSManagedObject class]) return YES;

__block BOOL result = NO;

[[self foundationClasses] enumerateObjectsUsingBlock:^(Class foundationClass, BOOL *stop) {

if ([c isSubclassOfClass:foundationClass]) {

result = YES;

*stop = YES;

}

}];

return result;

}

- (NSSet *)foundationClasses

{

if (classes == nil) {

// 集合中没有NSObject，因为几乎所有的类都是继承自NSObject，具体是不是NSObject需要特殊判断

classes = [NSSet setWithObjects:

[NSURL class],

[NSDate class],

[NSValue class],

[NSData class],

[NSError class],

[NSArray class],

[NSDictionary class],

[NSString class],

[NSAttributedString class], nil];

}

return classes;

}

31、几个常用权限判断

if ([CLLocationManager authorizationStatus] ==kCLAuthorizationStatusDenied) {

NSLog(@"没有定位权限");

}

AVAuthorizationStatus statusVideo = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];

if (statusVideo == AVAuthorizationStatusDenied) {

NSLog(@"没有摄像头权限");

}

//是否有麦克风权限

AVAuthorizationStatus statusAudio = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeAudio];

if (statusAudio == AVAuthorizationStatusDenied) {

NSLog(@"没有录音权限");

}

[PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {

if (status == PHAuthorizationStatusDenied) {

NSLog(@"没有相册权限");

}

}];

32、获取手机型号

+ (NSString *)getDeviceInfo {

struct utsname systemInfo;

uname(&systemInfo);

NSString *platform = [NSString stringWithCString:systemInfo.machine encoding:NSASCIIStringEncoding];

if ([platform isEqualToString:@"iPhone1,1"]) return @"iPhone 2G";

if ([platform isEqualToString:@"iPhone1,2"]) return @"iPhone 3G";

if ([platform isEqualToString:@"iPhone2,1"]) return @"iPhone 3GS";

if ([platform isEqualToString:@"iPhone3,1"]) return @"iPhone 4";

if ([platform isEqualToString:@"iPhone3,2"]) return @"iPhone 4";

if ([platform isEqualToString:@"iPhone3,3"]) return @"iPhone 4";

if ([platform isEqualToString:@"iPhone4,1"]) return @"iPhone 4S";

if ([platform isEqualToString:@"iPhone5,1"]) return @"iPhone 5";

if ([platform isEqualToString:@"iPhone5,2"]) return @"iPhone 5";

if ([platform isEqualToString:@"iPhone5,3"]) return @"iPhone 5c";

if ([platform isEqualToString:@"iPhone5,4"]) return @"iPhone 5c";

if ([platform isEqualToString:@"iPhone6,1"]) return @"iPhone 5s";

if ([platform isEqualToString:@"iPhone6,2"]) return @"iPhone 5s";

if ([platform isEqualToString:@"iPhone7,1"]) return @"iPhone 6 Plus";

if ([platform isEqualToString:@"iPhone7,2"]) return @"iPhone 6";

if ([platform isEqualToString:@"iPhone8,1"]) return @"iPhone 6s";

if ([platform isEqualToString:@"iPhone8,2"]) return @"iPhone 6s Plus";

// 日行两款手机型号均为日本独占，可能使用索尼FeliCa支付方案而不是苹果支付

if ([platform isEqualToString:@"iPhone9,1"]) return @"国行、日版、港行iPhone 7";

if ([platform isEqualToString:@"iPhone9,2"]) return @"港行、国行iPhone 7 Plus";

if ([platform isEqualToString:@"iPhone9,3"]) return @"美版、台版iPhone 7";

if ([platform isEqualToString:@"iPhone9,4"]) return @"美版、台版iPhone 7 Plus";

if ([platform isEqualToString:@"iPhone8,4"]) return @"iPhone SE";

if ([platform isEqualToString:@"iPod1,1"]) return @"iPod Touch 1G";

if ([platform isEqualToString:@"iPod2,1"]) return @"iPod Touch 2G";

if ([platform isEqualToString:@"iPod3,1"]) return @"iPod Touch 3G";

if ([platform isEqualToString:@"iPod4,1"]) return @"iPod Touch 4G";

if ([platform isEqualToString:@"iPod5,1"]) return @"iPod Touch 5G";

if ([platform isEqualToString:@"iPad1,1"]) return @"iPad 1G";

if ([platform isEqualToString:@"iPad2,1"]) return @"iPad 2";

if ([platform isEqualToString:@"iPad2,2"]) return @"iPad 2";

if ([platform isEqualToString:@"iPad2,3"]) return @"iPad 2";

if ([platform isEqualToString:@"iPad2,4"]) return @"iPad 2";

if ([platform isEqualToString:@"iPad2,5"]) return @"iPad Mini 1G";

if ([platform isEqualToString:@"iPad2,6"]) return @"iPad Mini 1G";

if ([platform isEqualToString:@"iPad2,7"]) return @"iPad Mini 1G";

if ([platform isEqualToString:@"iPad3,1"]) return @"iPad 3";

if ([platform isEqualToString:@"iPad3,2"]) return @"iPad 3";

if ([platform isEqualToString:@"iPad3,3"]) return @"iPad 3";

if ([platform isEqualToString:@"iPad3,4"]) return @"iPad 4";

if ([platform isEqualToString:@"iPad3,5"]) return @"iPad 4";

if ([platform isEqualToString:@"iPad3,6"]) return @"iPad 4";

if ([platform isEqualToString:@"iPad4,1"]) return @"iPad Air";

if ([platform isEqualToString:@"iPad4,2"]) return @"iPad Air";

if ([platform isEqualToString:@"iPad4,3"]) return @"iPad Air";

if ([platform isEqualToString:@"iPad4,4"]) return @"iPad Mini 2G";

if ([platform isEqualToString:@"iPad4,5"]) return @"iPad Mini 2G";

if ([platform isEqualToString:@"iPad4,6"]) return @"iPad Mini 2G";

if ([platform isEqualToString:@"i386"]) return @"iPhone Simulator";

if ([platform isEqualToString:@"x86_64"]) return @"iPhone Simulator";

return platform;

}

33、长按复制功能

- (void)viewDidLoad

{

[self.view addGestureRecognizer:[[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(pasteBoard:)]];

}

- (void)pasteBoard:(UILongPressGestureRecognizer *)longPress {

if (longPress.state == UIGestureRecognizerStateBegan) {

UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];

pasteboard.string = @"需要复制的文本";

}

34、cocoapods升级

在终端执行 sudo gem install -n / usr / local / bin cocoapods --pre

35、设置启动页后，依然显示之前的

删除app，手机重启，重新安装

36、判断图片类型

//通过图片Data数据第一个字节来获取图片扩展名

- (NSString *)contentTypeForImageData:(NSData *)data

{

uint8_t c;

[data getBytes:&c length:1];

switch (c)

{

case 0xFF:

return @"jpeg";

case 0x89:

return @"png";

case 0x47:

return @"gif";

case 0x49:

case 0x4D:

return @"tiff";

case 0x52:

if ([data length] < 12) {

return nil;

}

NSString *testString = [[NSString alloc] initWithData:[data subdataWithRange:NSMakeRange(0, 12)] encoding:NSASCIIStringEncoding];

if ([testString hasPrefix:@"RIFF"]

&& [testString hasSuffix:@"WEBP"])

{

return @"webp";

}

return nil;

}

return nil;

}

37、获取手机和app信息

NSDictionary *infoDictionary = [[NSBundle mainBundle] infoDictionary];

CFShow(infoDictionary);

// app名称

NSString *app_Name = [infoDictionary objectForKey:@"CFBundleDisplayName"];

// app版本

NSString *app_Version = [infoDictionary objectForKey:@"CFBundleShortVersionString"];

// app build版本

NSString *app_build = [infoDictionary objectForKey:@"CFBundleVersion"];

//手机序列号

NSString* identifierNumber = [[UIDevice currentDevice] uniqueIdentifier];

NSLog(@"手机序列号: %@",identifierNumber);

//手机别名：用户定义的名称

NSString* userPhoneName = [[UIDevice currentDevice] name];

NSLog(@"手机别名: %@", userPhoneName);

//设备名称

NSString* deviceName = [[UIDevice currentDevice] systemName];

NSLog(@"设备名称: %@",deviceName );

//手机系统版本

NSString* phoneVersion = [[UIDevice currentDevice] systemVersion];

NSLog(@"手机系统版本: %@", phoneVersion);

//手机型号

NSString* phoneModel = [[UIDevice currentDevice] model];

NSLog(@"手机型号: %@",phoneModel );

//地方型号（国际化区域名称）

NSString* localPhoneModel = [[UIDevice currentDevice] localizedModel];

NSLog(@"国际化区域名称: %@",localPhoneModel );

NSDictionary *infoDictionary = [[NSBundle mainBundle] infoDictionary];

// 当前应用名称

NSString *appCurName = [infoDictionary objectForKey:@"CFBundleDisplayName"];

NSLog(@"当前应用名称：%@",appCurName);

// 当前应用软件版本比如：1.0.1

NSString *appCurVersion = [infoDictionary objectForKey:@"CFBundleShortVersionString"];

NSLog(@"当前应用软件版本:%@",appCurVersion);

// 当前应用版本号码 int类型

NSString *appCurVersionNum = [infoDictionary objectForKey:@"CFBundleVersion"];

NSLog(@"当前应用版本号码：%@",appCurVersionNum);

38、获取一个类的所有属性

id LenderClass = objc_getClass("Lender");

unsigned int outCount, i;

objc_property_t *properties = class_copyPropertyList(LenderClass, &outCount);

for (i = 0; i < outCount; i++) {

objc_property_t property = properties[i];

fprintf(stdout, "%s %s\n", property_getName(property), property_getAttributes(property));

}

39、image拉伸

+ (UIImage *)resizableImage:(NSString *)imageName

{

UIImage *image = [UIImage imageNamed:imageName];

CGFloat imageW = image.size.width;

CGFloat imageH = image.size.height;

return [image resizableImageWithCapInsets:UIEdgeInsetsMake(imageH * 0.5, imageW * 0.5, imageH * 0.5, imageW * 0.5) resizingMode:UIImageResizingModeStretch];

}

40、JSON字符串转字典

+ (NSDictionary *)parseJSONStringToNSDictionary:(NSString *)JSONString {

NSData *JSONData = [JSONString dataUsingEncoding:NSUTF8StringEncoding];

NSDictionary *responseJSON = [NSJSONSerialization JSONObjectWithData:JSONData options:NSJSONReadingMutableLeaves error:nil];

return responseJSON;

}

41、身份证号验证

- (BOOL)validateIdentityCard {

BOOL flag;

if (self.length <= 0) {

flag = NO;

return flag;

}

NSString *regex2 = @"^(\\d{14}|\\d{17})(\\d|[xX])$";

NSPredicate *identityCardPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex2];

return [identityCardPredicate evaluateWithObject:self];

}

42、获取设备mac地址

+ (NSString *)macAddress {

int mib[6];

size_t len;

char *buf;

unsigned char *ptr;

struct if_msghdr *ifm;

struct sockaddr_dl *sdl;

mib[0] = CTL_NET;

mib[1] = AF_ROUTE;

mib[2] = 0;

mib[3] = AF_LINK;

mib[4] = NET_RT_IFLIST;

if((mib[5] = if_nametoindex("en0")) == 0) {

printf("Error: if_nametoindex error\n");

return NULL;

}

if(sysctl(mib, 6, NULL, &len, NULL, 0) < 0) {

printf("Error: sysctl, take 1\n");

return NULL;

}

if((buf = malloc(len)) == NULL) {

printf("Could not allocate memory. Rrror!\n");

return NULL;

}

if(sysctl(mib, 6, buf, &len, NULL, 0) < 0) {

printf("Error: sysctl, take 2");

return NULL;

}

ifm = (struct if_msghdr *)buf;

sdl = (struct sockaddr_dl *)(ifm + 1);

ptr = (unsigned char *)LLADDR(sdl);

NSString *outstring = [NSString stringWithFormat:@"%02X:%02X:%02X:%02X:%02X:%02X",

*ptr, *(ptr+1), *(ptr+2), *(ptr+3), *(ptr+4), *(ptr+5)];

free(buf);

return outstring;

}

43、导入自定义字体库

1、找到你想用的字体的 ttf 格式，拖入工程

2、在工程的plist中增加一行数组，“Fonts provided by application”

3、为这个key添加一个item，value为你刚才导入的ttf文件名

4、直接使用即可：label.font = [UIFont fontWithName:@"你刚才导入的ttf文件名" size:20.0]；

44、拿到当前正在显示的控制器，不管是push进去的，还是present进去的都能拿到

- (UIViewController *)getVisibleViewControllerFrom:(UIViewController*)vc {

if ([vc isKindOfClass:[UINavigationController class]]) {

return [self getVisibleViewControllerFrom:[((UINavigationController*) vc) visibleViewController]];

}else if ([vc isKindOfClass:[UITabBarController class]]){

return [self getVisibleViewControllerFrom:[((UITabBarController*) vc) selectedViewController]];

} else {

if (vc.presentedViewController) {

return [self getVisibleViewControllerFrom:vc.presentedViewController];

} else {

return vc;

}

45、runtime为一个类动态添加属性

// 动态添加属性的本质是: 让对象的某个属性与值产生关联

objc_setAssociatedObject(self, WZBPlaceholderViewKey, placeholderView, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

46、获取runtime为一个类动态添加的属性

objc_getAssociatedObject(self, WZBPlaceholderViewKey);

47、KVO监听某个对象的属性

// 添加监听者

[self addObserver:self forKeyPath:property options:NSKeyValueObservingOptionNew context:nil];

// 当监听的属性值变化的时候会来到这个方法

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {

if ([keyPath isEqualToString:@"property"]) {

[self textViewTextChange];

} else {

}

48、Reachability判断网络状态

NetworkStatus status = [[Reachability reachabilityForInternetConnection] currentReachabilityStatus];

if (status == NotReachable) {

NSLog(@"当前设备无网络");

}

if (status == ReachableViaWiFi) {

NSLog(@"当前wifi网络");

}

if (status == ReachableViaWWAN) {

NSLog(@"当前蜂窝移动网络");

}

49、AFNetworking监听网络状态

// 监听网络状况

AFNetworkReachabilityManager *mgr = [AFNetworkReachabilityManager sharedManager];

[mgr setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {

switch (status) {

case AFNetworkReachabilityStatusUnknown:

break;

case AFNetworkReachabilityStatusNotReachable: {

[SVProgressHUD showInfoWithStatus:@"当前设备无网络"];

}

break;

case AFNetworkReachabilityStatusReachableViaWiFi:

[SVProgressHUD showInfoWithStatus:@"当前Wi-Fi网络"];

break;

case AFNetworkReachabilityStatusReachableViaWWAN:

[SVProgressHUD showInfoWithStatus:@"当前蜂窝移动网络"];

break;

default:

break;

}

}];

[mgr startMonitoring];

50、透明颜色不影响子视图透明度

[UIColor colorWithRed:<#(CGFloat)#> green:<#(CGFloat)#> blue:<#(CGFloat)#> alpha:<#(CGFloat)#>];

51、取图片某一点的颜色

if (point.x < 0 || point.y < 0) return nil;

CGImageRef imageRef = self.CGImage;

NSUInteger width = CGImageGetWidth(imageRef);

NSUInteger height = CGImageGetHeight(imageRef);

if (point.x >= width || point.y >= height) return nil;

unsigned char *rawData = malloc(height * width * 4);

if (!rawData) return nil;

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

NSUInteger bytesPerPixel = 4;

NSUInteger bytesPerRow = bytesPerPixel * width;

NSUInteger bitsPerComponent = 8;

CGContextRef context = CGBitmapContextCreate(rawData,

width,

height,

bitsPerComponent,

bytesPerRow,

colorSpace,

kCGImageAlphaPremultipliedLast

| kCGBitmapByteOrder32Big);

if (!context) {

free(rawData);

return nil;

}

CGColorSpaceRelease(colorSpace);

CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);

CGContextRelease(context);

int byteIndex = (bytesPerRow * point.y) + point.x * bytesPerPixel;

CGFloat red = (rawData[byteIndex] * 1.0) / 255.0;

CGFloat green = (rawData[byteIndex + 1] * 1.0) / 255.0;

CGFloat blue = (rawData[byteIndex + 2] * 1.0) / 255.0;

CGFloat alpha = (rawData[byteIndex + 3] * 1.0) / 255.0;

UIColor *result = nil;

result = [UIColor colorWithRed:red green:green blue:blue alpha:alpha];

free(rawData);

return result;

52、根据bundle中的文件名读取图片

+ (UIImage *)imageWithFileName:(NSString *)name {

NSString *extension = @"png";

NSArray *components = [name componentsSeparatedByString:@"."];

if ([components count] >= 2) {

NSUInteger lastIndex = components.count - 1;

extension = [components objectAtIndex:lastIndex];

name = [name substringToIndex:(name.length-(extension.length+1))];

}

// 如果为Retina屏幕且存在对应图片，则返回Retina图片，否则查找普通图片

if ([UIScreen mainScreen].scale == 2.0) {

name = [name stringByAppendingString:@"@2x"];

NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:extension];

if (path != nil) {

return [UIImage imageWithContentsOfFile:path];

}

if ([UIScreen mainScreen].scale == 3.0) {

name = [name stringByAppendingString:@"@3x"];

NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:extension];

if (path != nil) {

return [UIImage imageWithContentsOfFile:path];

}

NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:extension];

if (path) {

return [UIImage imageWithContentsOfFile:path];

}

return nil;

}

53、合并两个图片

+ (UIImage*)mergeImage:(UIImage*)firstImage withImage:(UIImage*)secondImage {

CGImageRef firstImageRef = firstImage.CGImage;

CGFloat firstWidth = CGImageGetWidth(firstImageRef);

CGFloat firstHeight = CGImageGetHeight(firstImageRef);

CGImageRef secondImageRef = secondImage.CGImage;

CGFloat secondWidth = CGImageGetWidth(secondImageRef);

CGFloat secondHeight = CGImageGetHeight(secondImageRef);

CGSize mergedSize = CGSizeMake(MAX(firstWidth, secondWidth), MAX(firstHeight, secondHeight));

UIGraphicsBeginImageContext(mergedSize);

[firstImage drawInRect:CGRectMake(0, 0, firstWidth, firstHeight)];

[secondImage drawInRect:CGRectMake(0, 0, secondWidth, secondHeight)];

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return image;

}

54、根据bundle中的图片名创建imageview

+ (id)imageViewWithImageNamed:(NSString*)imageName

{

return [[UIImageView alloc] initWithImage:[UIImage imageNamed:imageName]];

}

55、画水印

// 画水印

- (void) setImage:(UIImage *)image withWaterMark:(UIImage *)mark inRect:(CGRect)rect

{

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0)

{

UIGraphicsBeginImageContextWithOptions(self.frame.size, NO, 0.0);

}

//原图

[image drawInRect:self.bounds];

//水印图

[mark drawInRect:rect];

UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

self.image = newPic;

}

56、让label的文字内容显示在左上／右上／左下／右下／中心顶／中心底部

自定义UILabel

// 重写label的textRectForBounds方法

- (CGRect)textRectForBounds:(CGRect)bounds limitedToNumberOfLines:(NSInteger)numberOfLines {

CGRect rect = [super textRectForBounds:bounds limitedToNumberOfLines:numberOfLines];

switch (self.textAlignmentType) {

case WZBTextAlignmentTypeLeftTop: {

rect.origin = bounds.origin;

}

break;

case WZBTextAlignmentTypeRightTop: {

rect.origin = CGPointMake(CGRectGetMaxX(bounds) - rect.size.width, bounds.origin.y);

}

break;

case WZBTextAlignmentTypeLeftBottom: {

rect.origin = CGPointMake(bounds.origin.x, CGRectGetMaxY(bounds) - rect.size.height);

}

break;

case WZBTextAlignmentTypeRightBottom: {

rect.origin = CGPointMake(CGRectGetMaxX(bounds) - rect.size.width, CGRectGetMaxY(bounds) - rect.size.height);

}

break;

case WZBTextAlignmentTypeTopCenter: {

rect.origin = CGPointMake((CGRectGetWidth(bounds) - CGRectGetWidth(rect)) / 2, CGRectGetMaxY(bounds) - rect.origin.y);

}

break;

case WZBTextAlignmentTypeBottomCenter: {

rect.origin = CGPointMake((CGRectGetWidth(bounds) - CGRectGetWidth(rect)) / 2, CGRectGetMaxY(bounds) - CGRectGetMaxY(bounds) - rect.size.height);

}

break;

case WZBTextAlignmentTypeLeft: {

rect.origin = CGPointMake(0, rect.origin.y);

}

break;

case WZBTextAlignmentTypeRight: {

rect.origin = CGPointMake(rect.origin.x, 0);

}

break;

case WZBTextAlignmentTypeCenter: {

rect.origin = CGPointMake((CGRectGetWidth(bounds) - CGRectGetWidth(rect)) / 2, (CGRectGetHeight(bounds) - CGRectGetHeight(rect)) / 2);

}

break;

default:

break;

}

return rect;

}

- (void)drawTextInRect:(CGRect)rect {

CGRect textRect = [self textRectForBounds:rect limitedToNumberOfLines:self.numberOfLines];

[super drawTextInRect:textRect];

}

57、使用performSelector:调用函数，内存泄漏问题

当我们在开发中使用[obj performSelector:NSSelectorFromString(@"aMethod")];这类方法时可能会收到一个警告"performSelector may cause a leak because its selector is unknown".

是因为编译器不清楚这个对象能不能相应这个方法，如果不能，则是不安全的，而且编译器也不清楚该怎么处理这个方法的返回值！

使用以下代码调用即可：

if (! obj) { return; }

SEL selector = NSSelectorFromString(@"aMethod");

IMP imp = [obj methodForSelector:selector];

void (*func)(id, SEL) = (void *)imp;

func(obj, selector);

或者：

SEL selector = NSSelectorFromString(@"aMethod");

((void (*)(id, SEL))[obj methodForSelector:selector])(obj, selector);

58、一个字符串是否包含另一个字符串

// 方法1

if ([str1 containsString:str2]) {

NSLog(@"str1包含str2");

} else {

NSLog(@"str1不包含str2");

}

// 方法2

if ([str1 rangeOfString: str2].location == NSNotFound) {

NSLog(@"str1不包含str2");

} else {

NSLog(@"str1包含str2");

}

59、当删除一个从xib拖出来的属性时，一定记得把xib中对应的线也删掉，不然会报类似[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key的crash

点击这个叉号删除

60、真机测试的时候报错：Could not launch "你的 App"，process launch failed: Security

因为你的app没有上线，iOS9开始，需要手动信任Xcode生成的描述文件，打开手机设置->通用->描述文件->点击你的app的描述文件->点击信任

61、真机测试的时候报错：Could not find Developer Disk Image

这是因为你的设备系统版本大于Xcode能兼容的系统版本，比如你的设备是iOS10.3，而Xcode版本是8.2（Xcode8.2最大兼容iOS10.2），就会报这个错误。解决办法就是升级Xcode

62、移除字符串中的空格和换行

+ (NSString *)removeSpaceAndNewline:(NSString *)str {

NSString *temp = [str stringByReplacingOccurrencesOfString:@" " withString:@""];

temp = [temp stringByReplacingOccurrencesOfString:@"\r" withString:@""];

temp = [temp stringByReplacingOccurrencesOfString:@"\n" withString:@""];

return temp;

}

63、判断字符串中是否有空格

+ (BOOL)isBlank:(NSString *)str {

NSRange _range = [str rangeOfString:@" "];

if (_range.location != NSNotFound) {

//有空格

return YES;

} else {

//没有空格

return NO;

}

64、获取一个视频的第一帧图片

NSURL *url = [NSURL URLWithString:filepath];

AVURLAsset *asset1 = [[AVURLAsset alloc] initWithURL:url options:nil];

AVAssetImageGenerator *generate1 = [[AVAssetImageGenerator alloc] initWithAsset:asset1];

generate1.appliesPreferredTrackTransform = YES;

NSError *err = NULL;

CMTime time = CMTimeMake(1, 2);

CGImageRef oneRef = [generate1 copyCGImageAtTime:time actualTime:NULL error:&err];

UIImage *one = [[UIImage alloc] initWithCGImage:oneRef];

return one;

65、获取视频的时长

+ (NSInteger)getVideoTimeByUrlString:(NSString *)urlString {

NSURL *videoUrl = [NSURL URLWithString:urlString];

AVURLAsset *avUrl = [AVURLAsset assetWithURL:videoUrl];

CMTime time = [avUrl duration];

int seconds = ceil(time.value/time.timescale);

return seconds;

}

66、字符串是否为空

+ (BOOL)isEqualToNil:(NSString *)str {

return str.length <= 0 || [str isEqualToString:@""] || !str;

}

67、将app上传到App Store的时候通常会遇到这个问题

try again

很多人说这事苹果爸爸服务器问题，重复尝试几次，总会成功的！

但是经过尝试发现如果使用Application Loader上传成功率就非常高，所以还是推荐把ipa文件导出直接用Application Loader上传。

如果Application Loader也不行，需要检查下自己的网络，有时候vpn也会提高速度。

68、isKindOfClass和isMemberOfClass的区别

isKindOfClass可以判断某个对象是否属于某个类，或者这个类的子类。

isMemberOfClass更加精准，它只能判断这个对象类型是否为这个类(不能判断子类)

69、__block

当一个局部变量需要在block里改变时，需要在定义时加上__block修饰，具体请看官方文档http://developer.apple.com/library/ios/documentation/cocoa/Conceptual/Blocks/Articles/bxVariables.html#//apple_ref/doc/uid/TP40007502-CH6-SW6

70、-[ViewController aMethod:]: unrecognized selector sent to instance 0x7fe91e607fb0

这是一个经典错误，ViewController不能响应aMethod这个方法，错误原因可能viewController文件中没有实现aMethod这个方法

71、UITableView () failed to obtain a cell from its dataSource ()

这个错误原因是tableView的代理方法-tableView:cellForRowAtIndexPath:需要返回一个UITableViewCell,而你返回了一个nil。另外这个地方返回值不是UITableViewCell类型也会导致崩溃

72、从NSURL中拿到链接字符串

NSString *urlString = myURL.absoluteString;

73、某个字体的高度

font.lineHeight;

74、删除某个view所有的子视图

[[someView subviews]

makeObjectsPerformSelector:@selector(removeFromSuperview)];

75、删除NSUserDefaults所有记录

//方法一

NSString *appDomain = [[NSBundle mainBundle] bundleIdentifier];

[[NSUserDefaults standardUserDefaults] removePersistentDomainForName:appDomain];

//方法二

- (void)resetDefaults {

NSUserDefaults * defs = [NSUserDefaults standardUserDefaults];

NSDictionary * dict = [defs dictionaryRepresentation];

for (id key in dict) {

[defs removeObjectForKey:key];

}

[defs synchronize];

}

// 方法三

[[NSUserDefaults standardUserDefaults] setPersistentDomain:[NSDictionary dictionary] forName:[[NSBundle mainBundle] bundleIdentifier]];

75、禁用系统滑动返回功能

- (void)viewDidAppear:(BOOL)animated

{

[super viewDidAppear:animated];

if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {self.navigationController.interactivePopGestureRecognizer.delegate = self;

}

- (void)viewWillDisappear:(BOOL)animated {

[super viewWillDisappear:animated];

if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {self.navigationController.interactivePopGestureRecognizer.delegate = nil;

}

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer

{

return NO;

}

76、UILabel设置内边距

子类化UILabel，重写drawTextInRect方法

- (void)drawTextInRect:(CGRect)rect {

// 边距，上左下右

UIEdgeInsets insets = {0, 5, 0, 5};

[super drawTextInRect:UIEdgeInsetsInsetRect(rect, insets)];

}

77、UILabel设置文字描边

子类化UILabel，重写drawTextInRect方法

- (void)drawTextInRect:(CGRect)rect

{

CGContextRef c = UIGraphicsGetCurrentContext();

// 设置描边宽度

CGContextSetLineWidth(c, 1);

CGContextSetLineJoin(c, kCGLineJoinRound);

CGContextSetTextDrawingMode(c, kCGTextStroke);

// 描边颜色

self.textColor = [UIColor redColor];

[super drawTextInRect:rect];

// 文本颜色

self.textColor = [UIColor yellowColor];

CGContextSetTextDrawingMode(c, kCGTextFill);

[super drawTextInRect:rect];

}

78、UIView背景颜色渐变

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 100)];

[self.view addSubview:view];

CAGradientLayer *gradient = [CAGradientLayer layer];

gradient.frame = view.bounds;

gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor blackColor] CGColor], (id)[[UIColor whiteColor] CGColor], nil];

[view.layer insertSublayer:gradient atIndex:0];

79、删除Xcode Derived data缓存数据

依次点击Xcode -> Preferences -> location，然后点击 Derived data路径后到小箭头，删除这个文件夹下的数据就可以了，如图

Xcode Derived data

80、获取view的坐标在整个window上的位置

// v上的(0, 0)点在toView上的位置

CGPoint point = [v convertPoint:CGPointMake(0, 0) toView:[UIApplication sharedApplication].windows.lastObject];

或者

CGPoint point = [v.superview convertPoint:v.frame.origin toView:[UIApplication sharedApplication].windows.lastObject];

81、提交App Store审核程序限制

您的应用程序的未压缩大小必须小于4GB。每个Mach-O可执行文件（例如app_name.app/app_name）不能超过这些限制：

对于MinimumOSVersion小于7.0的应用程序：

TEXT二进制文件中所有部分的总数最多为80 MB 。

对于MinimumOSVersion7.x到8.x的应用程序：

TEXT对于二进制文件中每个体系结构片段的每个片段，最大为60 MB 。

对于MinimumOSVersion9.0或更高版本的应用程序：__TEXT二进制文件中所有部分的总数最多为500 MB 。参阅：iTunes Connect开发者指南

82、修改UISegmentedControl的字体大小

[segment setTitleTextAttributes:@{NSFontAttributeName : [UIFont systemFontOfSize:15.0f]} forState:UIControlStateNormal];

83、在非ViewController的地方弹出UIAlertController对话框

// 最好抽成一个分类

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:@"message" preferredStyle:UIAlertControllerStyleAlert];

//...

id rootViewController = [UIApplication sharedApplication].delegate.window.rootViewController;

if([rootViewController isKindOfClass:[UINavigationController class]])

{

rootViewController = ((UINavigationController *)rootViewController).viewControllers.firstObject;

}

if([rootViewController isKindOfClass:[UITabBarController class]])

{

rootViewController = ((UITabBarController *)rootViewController).selectedViewController;

}

[rootViewController presentViewController:alertController animated:YES completion:nil];

84、获取一个view所属的控制器

// view分类方法

- (UIViewController *)belongViewController {

for (UIView *next = [self superview]; next; next = next.superview) {

UIResponder* nextResponder = [next nextResponder];

if ([nextResponder isKindOfClass:[UIViewController class]]) {

return (UIViewController *)nextResponder;

}

return nil;

}

85、UIWebView设置背景透明

[webView setBackgroundColor:[UIColor clearColor]];

[webView setOpaque:NO];

86、判断NSDate是不是今天

NSDateComponents *otherDay = [[NSCalendar currentCalendar] components:NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay fromDate:aDate];

NSDateComponents *today = [[NSCalendar currentCalendar] components:NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay fromDate:[NSDate date]];

if([today day] == [otherDay day] &&

[today month] == [otherDay month] &&

[today year] == [otherDay year] &&

[today era] == [otherDay era]) {

// 是今天

}

87、比较两个颜色是否相等

- (BOOL)isEqualToColor:(UIColor *)otherColor {

CGColorSpaceRef colorSpaceRGB = CGColorSpaceCreateDeviceRGB();

UIColor *(^convertColorToRGBSpace)(UIColor*) = ^(UIColor *color) {

if (CGColorSpaceGetModel(CGColorGetColorSpace(color.CGColor)) == kCGColorSpaceModelMonochrome) {

const CGFloat *oldComponents = CGColorGetComponents(color.CGColor);

CGFloat components[4] = {oldComponents[0], oldComponents[0], oldComponents[0], oldComponents[1]};

CGColorRef colorRef = CGColorCreate( colorSpaceRGB, components );

UIColor *color = [UIColor colorWithCGColor:colorRef];

CGColorRelease(colorRef);

return color;

} else

return color;

};

UIColor *selfColor = convertColorToRGBSpace(self);

otherColor = convertColorToRGBSpace(otherColor);

CGColorSpaceRelease(colorSpaceRGB);

return [selfColor isEqual:otherColor];

}

88、tableViewCell分割线顶到头

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {

[cell setSeparatorInset:UIEdgeInsetsZero];

[cell setLayoutMargins:UIEdgeInsetsZero];

cell.preservesSuperviewLayoutMargins = NO;

}

- (void)viewDidLayoutSubviews {

[self.tableView setSeparatorInset:UIEdgeInsetsZero];

[self.tableView setLayoutMargins:UIEdgeInsetsZero];

}

89、不让控制器的view随着控制器的xib拉伸或压缩

self.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

90、cocoaPods报错 : [!] Unable to add a source with urlhttps://github.com/CocoaPods/Specs.gitnamed master-1.

You can try adding it manually in ~/.cocoapods/repos or via pod repo add.

解决方法：这是因为电脑里安装了另外一个Xcode导致cocoapods找不到路径了

在终端执行 sudo xcode-select -switch /Applications/Xcode.app 即可

91、安装cocoapods的时候出现 ERROR: While executing gem ... (Errno::EPERM)

Operation not permitted - /usr/bin/pod

解决办法：直接在终端执行 sudo gem install -n /usr/local/bin cocoapods

92、在状态栏增加网络请求的菊花，类似safari加载网页的时候状态栏菊花

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

93、检查一个rect是否包含一个point

// point是否在rect内

BOOL isContains = CGRectContainsPoint(rect, point);

94、在指定的宽度下，让UILabel自动设置最佳font

label.adjustsFontSizeToFitWidth = YES;

95、将一个image保存在相册中

UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

或者

#import

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{

PHAssetChangeRequest *changeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:image];

changeRequest.creationDate = [NSDate date];

} completionHandler:^(BOOL success, NSError *error) {

if (success) {

NSLog(@"successfully saved");

}

else {

NSLog(@"error saving to photos: %@", error);

}

}];

96、UITextView中打开或禁用复制，剪切，选择，全选等功能

// 继承UITextView重写这个方法

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender

{

// 返回NO为禁用，YES为开启

// 粘贴

if (action == @selector(paste:)) return NO;

// 剪切

if (action == @selector(cut:)) return NO;

// 复制

if (action == @selector(copy:)) return NO;

// 选择

if (action == @selector(select:)) return NO;

// 选中全部

if (action == @selector(selectAll:)) return NO;

// 删除

if (action == @selector(delete:)) return NO;

// 分享

if (action == @selector(share)) return NO;

return [super canPerformAction:action withSender:sender];

}