iOS8.0以后的相册

在 iOS 8.0 后, 使用the Photos framework 代替 the Assets Library framework , The Photos framework 提供更特色和更好的表现 在使用 photo library

- (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")
        Log(@"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

    // 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;

    // 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) {
            Log(@"保存[图片]到[相机胶卷]中失败!失败信息-%@", error);
            return;
        }

        // 获得曾经创建过的相簿
        PHAssetCollection *createdAssetCollection = [self createdAssetCollection];
        if (createdAssetCollection) { // 曾经创建过相簿
            [[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) {
                    Log(@"添加[图片]到[相簿]失败!失败信息-%@", error);
                } else {
                    Log(@"成功添加[图片]到[相簿]!");
                }
            }];
        } else { // 没有创建过相簿
            [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
                // 2.创建"相簿"D
                // 创建相簿的请求
                assetCollectionLocalIdentifier = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:XMGAssetCollectionTitle].placeholderForCreatedAssetCollection.localIdentifier;
            } completionHandler:^(BOOL success, NSError * _Nullable error) {
                if (success == NO) {
                    Log(@"保存相簿失败!失败信息-%@", error);
                    return;
                }

                [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
                    // 3.添加"相机胶卷"中的图片A到新建的"相簿"D中

                    // 获得相簿
                    PHAssetCollection *assetCollection = [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[assetCollectionLocalIdentifier] options:nil].lastObject;

                    // 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:assetCollection];

                    // 添加图片到相簿
                    [request addAssets:@[asset]];
                } completionHandler:^(BOOL success, NSError * _Nullable error) {
                    if (success == NO) {
                        Log(@"添加[图片]到[相簿]失败!失败信息-%@", error);
                    } else {
                        Log(@"成功添加[图片]到[相簿]!");
                    }
                }];
            }];
        }
    }];
}

/**
 *  获得曾经创建过的相簿
 */
- (PHAssetCollection *)createdAssetCollection
{
    PHFetchResult<PHAssetCollection *> *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];

    for (PHAssetCollection *assetCollection in assetCollections) {
        if ([assetCollection.localizedTitle isEqualToString:XMGAssetCollectionTitle]) {
            return assetCollection;
        }
    }

    return nil;
}