保存照片是一件极其恶心的事！下面介绍一下照片的存和取

iOS 10推出了访问权限，在plist里添加即可

<!-- 相册 --> 
<key>NSPhotoLibraryUsageDescription</key> 
<string>App需要您的同意,才能访问相册</string> 
<!-- 相机 --> 
<key>NSCameraUsageDescription</key> 
<string>App需要您的同意,才能访问相机</string> 
<!-- 麦克风 --> 
<key>NSMicrophoneUsageDescription</key> 
<string>App需要您的同意,才能访问麦克风</string> 
<!-- 位置 --> 
<key>NSLocationUsageDescription</key> 
<string>App需要您的同意,才能访问位置</string> 
<!-- 在使用期间访问位置 --> 
<key>NSLocationWhenInUseUsageDescription</key> 
<string>App需要您的同意,才能在使用期间访问位置</string> 
<!-- 始终访问位置 --> 
<key>NSLocationAlwaysUsageDescription</key> 
<string>App需要您的同意,才能始终访问位置</string> 
<!-- 日历 --> 
<key>NSCalendarsUsageDescription</key> 
<string>App需要您的同意,才能访问日历</string> 
<!-- 提醒事项 --> 
<key>NSRemindersUsageDescription</key> 
<string>App需要您的同意,才能访问提醒事项</string> 
<!-- 运动与健身 --> 
<key>NSMotionUsageDescription</key> <string>App需要您的同意,才能访问运动与健身</string> 
<!-- 健康更新 --> 
<key>NSHealthUpdateUsageDescription</key> 
<string>App需要您的同意,才能访问健康更新 </string> 
<!-- 健康分享 --> 
<key>NSHealthShareUsageDescription</key> 
<string>App需要您的同意,才能访问健康分享</string> 
<!-- 蓝牙 --> 
<key>NSBluetoothPeripheralUsageDescription</key> 
<string>App需要您的同意,才能访问蓝牙</string> 
<!-- 媒体资料库 --> 
<key>NSAppleMusicUsageDescription</key> 
<string>App需要您的同意,才能访问媒体资料库</string>

<h1>1.照片的存储(这里会用两个方法实现，一种是与其他照片一样存在set里，另一种是新创建一个set存储)</h1>

• 点击图片
• 控制器传参
• 显示在ScrollView上, 并设置好图片的宽高

方法一

self.imageView.userInteractionEnabled = YES;
    [self.imageView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(seeBig)]];

ZJSeeBigViewController *seeBig = [[ZJSeeBigViewController alloc] init];
    seeBig.topic = self.topic;
    [[UIApplication sharedApplication].keyWindow.rootViewController presentViewController:seeBig animated:YES completion:nil];

// scrollView
    UIScrollView *scrollView = [[UIScrollView alloc] init];
    scrollView.delegate = self;
    scrollView.frame = [UIScreen mainScreen].bounds;
    [self.view insertSubview:scrollView atIndex:0];
    
    // scrollView.backgroundColor = [UIColor redColor];
    // scrollView.frame = self.view.bounds;
    // scrollView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
    
    // imageView
    UIImageView *imageView = [[UIImageView alloc] init];
    [imageView sd_setImageWithURL:[NSURL URLWithString:self.topic.large_image] completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
        if (image == nil) return; // 图片下载失败
        self.saveButton.enabled = YES;
    }];
    [scrollView addSubview:imageView];
    
    imageView.xmg_width = scrollView.xmg_width;
    imageView.xmg_height = self.topic.height * imageView.xmg_width / self.topic.width;
    imageView.xmg_x = 0;
    
    if (imageView.xmg_height >= scrollView.xmg_height) { // 图片高度超过整个屏幕
        imageView.xmg_y = 0;
        // 滚动范围
        scrollView.contentSize = CGSizeMake(0, imageView.xmg_height);
    } else { // 居中显示
        imageView.xmg_centerY = scrollView.xmg_height * 0.5;
    }
    self.imageView = imageView;

    // 缩放比例
    CGFloat scale =  self.topic.width / imageView.xmg_width;
    if (scale > 1.0) {
        scrollView.maximumZoomScale = scale;
    }

- (IBAction)save {

    UIImageWriteToSavedPhotosAlbum(self.imageView.image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    if (error) {
        [SVProgressHUD showErrorWithStatus:@"图片保存失败!"];
    } else {
        [SVProgressHUD showSuccessWithStatus:@"图片保存成功!"];
    }
}

方法二(这里涉及到一个新的类库<Photos/Photos.h> 在保存照片的时候，我们需要先判断手机里是否有改软件已经存储的collectionSet 如果有直接往里存，没有要创建，保存之前会涉及到一个用户quan)

#import "XMGSeeBigViewController.h"
#import "XMGTopic.h"
#import <UIImageView+WebCache.h>

// #import <AssetsLibrary/AssetsLibrary.h> // iOS9开始废弃
#import <Photos/Photos.h> // iOS9开始推荐

#import <SVProgressHUD.h>

@interface XMGSeeBigViewController () <UIScrollViewDelegate>
/** 图片控件 */
@property (nonatomic, weak) UIImageView *imageView;
@property (weak, nonatomic) IBOutlet UIButton *saveButton;
@end

@implementation XMGSeeBigViewController

static NSString * XMGAssetCollectionTitle = @"5期-百思不得姐";

//点击保存按钮
- (IBAction)save {
    /*
     PHAuthorizationStatusNotDetermined,     用户还没有做出选择
     PHAuthorizationStatusDenied,            用户拒绝当前应用访问相册(用户当初点击了"不允许")
     PHAuthorizationStatusAuthorized         用户允许当前应用访问相册(用户当初点击了"好")
     PHAuthorizationStatusRestricted,        因为家长控制, 导致应用无法方法相册(跟用户的选择没有关系)
     */
    
    // 判断授权状态
    PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
    if (status == PHAuthorizationStatusRestricted) { // 因为家长控制, 导致应用无法方法相册(跟用户的选择没有关系)
        [SVProgressHUD showErrorWithStatus:@"因为系统原因, 无法访问相册"];
    } else if (status == PHAuthorizationStatusDenied) { // 用户拒绝当前应用访问相册(用户当初点击了"不允许")
        XMGLog(@"提醒用户去[设置-隐私-照片-xxx]打开访问开关");
    } else if (status == PHAuthorizationStatusAuthorized) { // 用户允许当前应用访问相册(用户当初点击了"好")
        [self saveImage];
    } else if (status == PHAuthorizationStatusNotDetermined) { // 用户还没有做出选择
        // 弹框请求用户授权
        [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
            if (status == PHAuthorizationStatusAuthorized) { // 用户点击了好
                [self saveImage];
            }
        }];
    }
}

- (void)saveImage
{
    // PHAsset : 一个资源, 比如一张图片\一段视频
    // PHAssetCollection : 一个相簿
    
    // PHAsset的标识, 利用这个标识可以找到对应的PHAsset对象(图片对象)
    __block NSString *assetLocalIdentifier = nil;
    
    // 如果想对"相册"进行修改(增删改), 那么修改代码必须放在[PHPhotoLibrary sharedPhotoLibrary]的performChanges方法的block中
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        // 1.保存图片A到"相机胶卷"中
        // 创建图片的请求
        assetLocalIdentifier = [PHAssetCreationRequest creationRequestForAssetFromImage:self.imageView.image].placeholderForCreatedAsset.localIdentifier;
    } completionHandler:^(BOOL success, NSError * _Nullable error) {
        if (success == NO) {
            [self showError:@"保存图片失败!"];
            return;
        }
        
        // 2.获得相簿
        PHAssetCollection *createdAssetCollection = [self createdAssetCollection];
        if (createdAssetCollection == nil) {
            [self showError:@"创建相簿失败!"];
            return;
        }
        
        [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
            // 3.添加"相机胶卷"中的图片A到"相簿"D中
            
            // 获得图片
            PHAsset *asset = [PHAsset fetchAssetsWithLocalIdentifiers:@[assetLocalIdentifier] options:nil].lastObject;
            
            // 添加图片到相簿中的请求
            PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:createdAssetCollection];
            
            // 添加图片到相簿
            [request addAssets:@[asset]];
        } completionHandler:^(BOOL success, NSError * _Nullable error) {
            if (success == NO) {
                [self showError:@"保存图片失败!"];;
            } else {
                [self showSuccess:@"保存图片成功!"];;
            }
        }];
    }];
}

/**
 *  获得相簿
 */
- (PHAssetCollection *)createdAssetCollection
{
    // 从已存在相簿中查找这个应用对应的相簿
    PHFetchResult<PHAssetCollection *> *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    for (PHAssetCollection *assetCollection in assetCollections) {
        if ([assetCollection.localizedTitle isEqualToString:XMGAssetCollectionTitle]) {
            return assetCollection;
        }
    }
    
    // 没有找到对应的相簿, 得创建新的相簿
    
    // 错误信息
    NSError *error = nil;
    
    // PHAssetCollection的标识, 利用这个标识可以找到对应的PHAssetCollection对象(相簿对象)
    __block NSString *assetCollectionLocalIdentifier = nil;
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        // 创建相簿的请求
        assetCollectionLocalIdentifier = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:XMGAssetCollectionTitle].placeholderForCreatedAssetCollection.localIdentifier;
    } error:&error];
    
    // 如果有错误信息
    if (error) return nil;
    
    // 获得刚才创建的相簿
    return [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[assetCollectionLocalIdentifier] options:nil].lastObject;
}

- (void)showSuccess:(NSString *)text
{
    dispatch_async(dispatch_get_main_queue(), ^{
        [SVProgressHUD showSuccessWithStatus:text];
    });
}

- (void)showError:(NSString *)text
{
    dispatch_async(dispatch_get_main_queue(), ^{
        [SVProgressHUD showErrorWithStatus:text];
    });
}

#pragma mark - <UIScrollViewDelegate>
/**
 *  返回一个scrollView的子控件进行缩放
 */
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return self.imageView;
}

<h1>2.利用UIImagePickerController取照片照片</h1>

iOS 获取图片有三种方法：

 1. 直接调用摄像头拍照
 2. 从相册中选择
 3. 从图库中选择

UIImagePickerController 类来获取图片视频，大体分为以下几个步骤：

 1. 初始化UIImagePickerController 类；
 2. 设置UIImagePickerController 实例的数据来源类型（下面解释）；
 3. 设置设置代理；
 4. 如果需要做图片修改的话设置allowsEditing =yes。

数据来源类型一共有三种：

enum {
     UIImagePickerControllerSourceTypePhotoLibrary ,//来自图库
     UIImagePickerControllerSourceTypeCamera ,//来自相机
     UIImagePickerControllerSourceTypeSavedPhotosAlbum //来自相册
     };

获取图片首先签订两个协议

@interface MainViewController ()<UIImagePickerControllerDelegate,UINavigationControllerDelegate>

在点击方法内模态推出UIImagePickerController
从相册选取（需给用户选择哪种方式获取图片）

/**
 *  利用UIImagePickerController挑选图片
 */
- (void)getImageFromIpc
{
    // UIImagePickerController : 可以从系统自带的App(照片\相机)中获得图片

    // 判断相册是否可以打开
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) return;

    UIImagePickerController *ipc = [[UIImagePickerController alloc] init];
    // 打开照片应用(显示所有相簿)
    ipc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    // 打开照片应用(只显示"时刻"这个相簿)
    // ipc.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
    // 照相机
    // ipc.sourceType = UIImagePickerControllerSourceTypeCamera;
    ipc.delegate = self;
    [self presentViewController:ipc animated:YES completion:nil];
}

#pragma mark - <UIImagePickerControllerDelegate>
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
{
    // 销毁控制器
    [picker dismissViewControllerAnimated:YES completion:nil];

    // 设置图片
    self.imageView.image = info[UIImagePickerControllerOriginalImage];
}

实现代理方法

//选择完图片后会回调 didFinishPickingMediaWithInfo 这个方法
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info {
NSLog(@"info = %@",info);
//隐藏控制器
  [picker dismissViewControllerAnimated:YES completion:nil];
//给imageView 赋值图片
  imageView.image = [info objectForKey:UIImagePickerControllerEditedImage];
}
//导航条上面的 Cancel 的点击方法
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
//隐藏控制器
  [picker dismissViewControllerAnimated:YES completion:nil];
}