獲取Photos.app中的圖像數量？

Question

我知道可以通過使用ALAssetsLibrary獲取Photos.app中的圖像，但是如何獲取Photos.app中的照片總數？

差不多我試圖檢查的照片的數量，因爲我得到的Photos.app最後一個圖像從這個問題的代碼：Get last image from Photos.app?

因此，如果設備上有0的圖像，它贏得從上面的鏈接執行代碼。

無論如何，我怎麼能得到這個？

謝謝！

Answer 1

隨着新Photos框架，在iOS 8的推出，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; 
}]; 

這將不包括智能相冊（和，以我的經驗，他們沒有有效的「估計罪狀「），這樣你就可以獲取或者資產，以獲得實際計數：

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; 
}]; 

而且，順便說一句，如果你還沒有要求爲圖書館的授權，你應該這樣做，例如：

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

---

隨着老AssetsLibrary框架，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 

Answer 2

使用enumerateAssetsUsingBlock。每次結果不爲零，將它添加到一個數組（我會稱之爲self.arrayOfAssets）。然後，當你得到一個零結果（枚舉的終點）得到self.arrayOfAssets.count。

編輯：好的，所以這裏是來自另一個問題的代碼，幾個變化。使用enumerateAssetsUsingBlock: instead of enumerateAssetsAtIndexes:

給自己一個可變數組並將每個圖像放在那裏。

然後，當資產沒有信號表明枚舉已完成時，計數數組。

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init]; 

    self.allPhotos = [[NSMutableArray alloc] init]; 


    // Enumerate just the photos and videos group by using ALAssetsGroupSavedPhotos. 
    [library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos                 usingBlock:^(ALAssetsGroup *group, BOOL *stop) { 

    // Within the group enumeration block, filter to enumerate just photos. 
    [group setAssetsFilter:[ALAssetsFilter allPhotos]]; 

    [group enumerateAssetsUsingBlock:^(ALAsset *alAsset, NSUInteger index, BOOL *innerStop) { 

    // The end of the enumeration is signaled by asset == nil. 
    if (alAsset) { 
     ALAssetRepresentation *representation = [alAsset defaultRepresentation]; 
     UIImage *latestPhoto = [UIImage imageWithCGImage:[representation fullScreenImage]]; 
     [self.allPhotos addObject:latestPhoto]; 
    if (!asset){ 
      NSLog:(@"photos count:%d", self.allPhotos.count); 
      } 
     } 
    }]; 
} 
failureBlock: ^(NSError *error) { 
    // Typically you should handle an error more gracefully than this. 
    NSLog(@"No groups"); 
    }];