PHPhotoLibrary类

照片库使用单例发来请求授权 或者 查询授权状态

单例
+ (PHPhotoLibrary *)sharedPhotoLibrary;
获取授权状态
+ (PHAuthorizationStatus)authorizationStatus;
请求授权
+ (void)requestAuthorization:(void(^)(PHAuthorizationStatus status))handler;

同时注册照片库改变的观察者,接受到改变后执行照片库的观察者代理协议

#pragma mark - Change Handling

- (void)registerChangeObserver:(id<PHPhotoLibraryChangeObserver>)observer;
- (void)unregisterChangeObserver:(id<PHPhotoLibraryChangeObserver>)observer;

@protocol PHPhotoLibraryChangeObserver <NSObject>

- (void)photoLibraryDidChange:(PHChange *)changeInstance;

@end

保存图片方式

// 保存到相册
- (void)savePhotoToAlbum:(UIImage*)image
         completionBlock:(nullable void (^)(WBPKPhoto *photo,NSError *error))completionBlock {
    @autoreleasepool {
        __block PHObjectPlaceholder *assetPlaceholder = nil;
        dispatch_semaphore_wait(self.savePhotoToAlbumSemaphore, DISPATCH_TIME_FOREVER);
        [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
            PHAssetChangeRequest *changeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:image];
            assetPlaceholder = changeRequest.placeholderForCreatedAsset;
        } completionHandler:^(BOOL success, NSError * _Nullable error) {
            PHFetchResult *result = nil;
            if (success && assetPlaceholder) {
                result = [PHAsset fetchAssetsWithLocalIdentifiers:@[assetPlaceholder.localIdentifier] options:nil];
                WBPKPhoto *photo = [[WBPKPhoto alloc] initWithPHAsset:result.firstObject];
                if (completionBlock) completionBlock(photo,error);
            } else {
                if (completionBlock) completionBlock(nil,error);
            }
            dispatch_semaphore_signal(self.savePhotoToAlbumSemaphore);
        }];
    }
}