<Photos/Photos.h>
PHFetchResult  资源集合，类似数组
PHAssetCollection 一个相簿
PHAsset 代表照片库中的一个资源，可转化成缩略图 UIImage

//获取一个相簿，内容是所有照片
//配置获取参数：按创建时间升序
PHFetchOptions *allPhotosOptions = [[PHFetchOptions alloc] init]; 
allPhotosOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]]; 
//获取资源集合通过可选条件
PHFetchResult<PHAsset *> *allPhotos = [PHAsset fetchAssetsWithOptions:allPhotosOptions];
//转换成相簿Model
AlbumsModel* allPhotosModel = [[AlbumsModel alloc] initWithTitle:@"所有照片" assets:allPhotos];

//获取所有的内置相簿
PHFetchResult<PHAssetCollection *> *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
[smartAlbums enumerateObjectsUsingBlock:^(PHAssetCollection * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    PHFetchResult<PHAsset *> *tmpresult = [PHAsset fetchAssetsInAssetCollection:obj options:nil];
    if (tmpresult.count > 0)
    {
        AlbumsModel* tmpModel = [[AlbumsModel alloc] initWithTitle:obj.localizedTitle assets:tmpresult];
        [all addObject:tmpModel];
    }
}];

//获取所有用户自建相簿
PHFetchResult<PHAssetCollection *> *userAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil];    
[userAlbums enumerateObjectsUsingBlock:^(PHAssetCollection * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    PHFetchResult<PHAsset *> *tmpresult = [PHAsset fetchAssetsInAssetCollection:obj options:nil];
    if (tmpresult.count > 0)
    {
        AlbumsModel* tmpModel = [[AlbumsModel alloc] initWithTitle:obj.localizedTitle assets:tmpresult];
        [all addObject:tmpModel];
    }
}];

+ (void)requestImageForAsset:(PHAsset *)asset success:(void (^)(UIImage * image))success {
    //配置参数
    PHImageRequestOptions* options = [[PHImageRequestOptions alloc] init];
    options.synchronous = NO; //非同步请求
    options.resizeMode = PHImageRequestOptionsResizeModeFast; // 最快速的调整图像大小，有可能比给定大小略大
    options.deliveryMode = PHImageRequestOptionsDeliveryModeFastFormat; // 最快速的得到一个图像结果，可能会牺牲图像质量。
    
    [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:CGSizeMake(200, 200) contentMode:PHImageContentModeAspectFill options:options  resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
        success(result);
    }];
}

//默认选择单张
EasyPhotoPickerController* vc = [[EasyPhotoPickerController alloc] init];
[vc showPhotoLibraryWithTarget:self success:^(NSArray * _Nonnull images) {
    [self.headerIconView setImage:images.firstObject forState:UIControlStateNormal];
}];
 
//选择多张
EasyPhotoPickerController* vc = [[EasyPhotoPickerController alloc] init];
vc.allowsMultipleSelection = YES;
vc.maxCount = 9-self.photoPreview.listInfo.count+1;
[vc showPhotoLibraryWithTarget:self success:^(NSArray * _Nonnull images) {
    self.photoPreview.listInfo = [images mutableCopy];
}];