<统一收起键盘>

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

<数组去重>

NSArray *newArr = [oldArr valueForKeyPath:@“@distinctUnionOfObjects.self"];
@distinctUnionOfObjects.self  表示比较对象
@distinctUnionOfObjects.[key] 表示比较对象的任意keyboarded

<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"];

<给一个view截图>

UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0.0);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

<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];

<为UIView某个角添加圆角>

// 左上角和右下角添加圆角
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:(UIRectCornerTopLeft | UIRectCornerBottomRight) cornerRadii:CGSizeMake(20, 20)];
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.frame = view.bounds;
maskLayer.path = maskPath.CGPath;
view.layer.mask = maskLayer;

<拿到当前正在显示的控制器>

- (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;
        }
    }
}

<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];
}

<image添加倒影效果>

- (void)setImageShadow {
    CGRect frame = self.frame;
    frame.origin.y += (frame.size.height + 1);
     
    UIImageView *reflectionImageView = [[UIImageView alloc] initWithFrame:frame];
    self.clipsToBounds = TRUE;
    reflectionImageView.contentMode = self.contentMode;
    [reflectionImageView setImage:self.image];
    reflectionImageView.transform = CGAffineTransformMakeScale(1.0, -1.0);
 
    CALayer *reflectionLayer = [reflectionImageView layer];
    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.bounds = reflectionLayer.bounds;
    gradientLayer.position = CGPointMake(reflectionLayer.bounds.size.width / 2, reflectionLayer.bounds.size.height * 0.5);
    gradientLayer.colors = [NSArray arrayWithObjects:
                                                        (id)[[UIColor clearColor] CGColor],
                                                        (id)[[UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:0.3] CGColor], nil];
    gradientLayer.startPoint = CGPointMake(0.5,0.5);
    gradientLayer.endPoint = CGPointMake(0.5,1.0);
    reflectionLayer.mask = gradientLayer;
    [self.superview addSubview:reflectionImageView];
}

<添加图片水印>

// 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;
}

<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]];

<跳进app权限设置>

if (UIApplicationOpenSettingsURLString != NULL) {
    NSURL *url = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
    [[UIApplication sharedApplication] openURL:url];
}

<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];
        //自定义所有缓存大小
        count += fileDict.fileSize;
    }
    // 得到是字节  转化为M
    CGFloat totalSize = ((CGFloat)imageCacheSize+count)/1024/1024;
    return totalSize;
}   

<清理app缓存>

- (void)cleanAppCache {
    // 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];
}

<几个常用权限判断>

- (void)checkAppAuthorization{
    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");
    }
    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");
        }
    }];
}

<去除导航黑线>

// Swift:
navigationController?.navigationBar.setBackgroundImage(UIImage(), forBarMetrics: .Default)
navigationController?.navigationBar.shadowImage = UIImage()
// OC:
[self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];
[self.navigationController.navigationBar setShadowImage:[[UIImage alloc] init]];

<事件穿透到下一层视图>

self.isUserInteractionEnabled = false