获取Photos.app中的图像数量？

Question

我知道可以使用ALAssetsLibrary获取Photos.app中的图像,但如何获取Photos.app中的照片总数？

我正在尝试检查照片的数量,因为我正在使用此问题的代码获取Photos.app中的最后一张图片:从Photos.app获取最后一张图片？

因此,如果设备上有0个图像,它将不会执行上面链接中的代码.

无论如何我怎么能得到这个？

谢谢!

Answer 1

使用PhotosiOS 8中引入的新框架,您可以使用estimatedAssetCount:

NSUInteger __block estimatedCount = 0;

PHFetchResult <PHAssetCollection *> *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAny options:nil];
[collections enumerateObjectsUsingBlock:^(PHAssetCollection * _Nonnull collection, NSUInteger idx, BOOL * _Nonnull stop) {
    estimatedCount += collection.estimatedAssetCount;
}];

这将不包括智能相册(根据我的经验,他们没有有效的"估计计数"),因此您可以选择获取资产以获得实际数量:

NSUInteger __block count = 0;

// Get smart albums (e.g. "Camera Roll", "Recently Deleted", "Panoramas", "Screenshots", etc.

PHFetchResult <PHAssetCollection *> *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
[collections enumerateObjectsUsingBlock:^(PHAssetCollection * _Nonnull collection, NSUInteger idx, BOOL * _Nonnull stop) {
    PHFetchResult <PHAsset *> *assets = [PHAsset fetchAssetsInAssetCollection:collection options:nil];
    count += assets.count;
}];

// Get the standard albums (e.g. those from iTunes, created by apps, etc.), too

collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAny options:nil];
[collections enumerateObjectsUsingBlock:^(PHAssetCollection * _Nonnull collection, NSUInteger idx, BOOL * _Nonnull stop) {
    PHFetchResult <PHAsset *> *assets = [PHAsset fetchAssetsInAssetCollection:collection options:nil];
    count += assets.count;
}];

顺便说一句,如果你还没有请求授权库,你应该这样做,例如:

[PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
    if (status == PHAuthorizationStatusAuthorized) {
        // insert your image counting logic here
    }
}];

使用旧AssetsLibrary框架,您可以enumerateGroupsWithTypes:

NSUInteger __block count = 0;

[library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
    if (!group) {
        // asynchronous counting is done; examine `count` here
    } else {
        count += group.numberOfAssets;
    }
} failureBlock:^(NSError *err) {
    NSLog(@"err=%@", err);
}];

// but don't use `count` here, as the above runs asynchronously