objective-c - AssetsLibrary 框架在 iOS 8 上损坏

Question

我在 iOS 8 上遇到了一个问题， Assets 库框架似乎是 iOS 8 中的一个错误。如果我创建了一个名为“MyMedia”的相册，然后将其删除，那么当我再次尝试创建相册时，下面的这段代码返回“nil”，表明相册“MyMedia”存在，即使它不存在，因为我使用“照片”应用删除了它。

__block ALAssetsGroup *myGroup = nil;
__block BOOL addAssetDone = false;
NSString *albumName = @"MyMedia";
[assetsLib addAssetsGroupAlbumWithName:albumName
                           resultBlock:^(ALAssetsGroup *group) {
                               myGroup = group;
                               addAssetDone = true;
                           } failureBlock:^(NSError *error) {
                               NSLog( @"failed to create album: %@", albumName);
                               addAssetDone = true;
                           }];

while (!addAssetDone) {
    [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.05f]];
}
return myGroup; // returns nil if group has previously been created and then deleted

创建全新专辑“MyMedia2”时，同样的方法也适用。有没有其他人遇到过这个问题并且知道解决方法或解决方案？是迁移到新的“照片”框架的唯一解决方案还是我在这里做错了什么？请注意，此代码始终适用于 iOS7.X

其实重现这个问题的步骤如下->1. 卸载您拍摄照片并将其保存到自定义相册的应用2.在iOS Photos下删除保存有照片的自定义相册3. 安装您的应用4. 如果您使用该应用拍照或录制视频，它不会创建或存储它们。如果您查看 iOS 照片相册，自定义相册不存在，并且使用该应用拍摄的照片/视频都不存在。

Answer 1

我之前的回答是错误的。我还没有真正测试过。我终于弄清楚必须做什么，这很困难，但我让它工作了。这是我必须做的，才能让我的应用程序在 iOS 7.x.X 和 iOS 8.X.x 上运行，并创建一个之前已被应用程序删除的自定义相册 -->

1. 我写了两段代码:一段在 iOS 8.x.x 上使用 Photos 框架，另一段在 iOS 7.x.x 上使用 AssetsLibrary 框架

2. Sp 该应用程序可以在两个 iOS 版本上运行，我将该应用程序链接到照片框架，但随后将其从必需更改为可选，因此它不会在 iOS 7.x.x 上加载

3. 因为在 iOS 7.x.x 上无法在运行时直接调用 Photos 框架代码，我不得不更改它以便它在运行时动态加载类、函数(和 block !)

   <

这是在 iPhone 上运行时可以运行的代码块。这应该也适用于模拟器 -->

// PHPhotoLibrary_class will only be non-nil on iOS 8.x.x
Class PHPhotoLibrary_class = NSClassFromString(@"PHPhotoLibrary");

if (PHPhotoLibrary_class) {

   /**
    *
    iOS 8..x. . code that has to be called dynamically at runtime and will not link on iOS 7.x.x ...

    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title];
    } completionHandler:^(BOOL success, NSError *error) {
        if (!success) {
            NSLog(@"Error creating album: %@", error);
        }
    }];
    */

    // dynamic runtime code for code chunk listed above            
    id sharedPhotoLibrary = [PHPhotoLibrary_class performSelector:NSSelectorFromString(@"sharedPhotoLibrary")];

    SEL performChanges = NSSelectorFromString(@"performChanges:completionHandler:");

    NSMethodSignature *methodSig = [sharedPhotoLibrary methodSignatureForSelector:performChanges];

    NSInvocation* inv = [NSInvocation invocationWithMethodSignature:methodSig];
    [inv setTarget:sharedPhotoLibrary];
    [inv setSelector:performChanges];

    void(^firstBlock)() = ^void() {
        Class PHAssetCollectionChangeRequest_class = NSClassFromString(@"PHAssetCollectionChangeRequest");
        SEL creationRequestForAssetCollectionWithTitle = NSSelectorFromString(@"creationRequestForAssetCollectionWithTitle:");
        [PHAssetCollectionChangeRequest_class performSelector:creationRequestForAssetCollectionWithTitle withObject:albumName];

    };

    void (^secondBlock)(BOOL success, NSError *error) = ^void(BOOL success, NSError *error) {
       if (success) {
           [assetsLib enumerateGroupsWithTypes:ALAssetsGroupAlbum usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
               if (group) {
                   NSString *name = [group valueForProperty:ALAssetsGroupPropertyName];
                   if ([albumName isEqualToString:name]) {
                       groupFound = true;
                       handler(group, nil);
                   }
               }
           } failureBlock:^(NSError *error) {
               handler(nil, error);
           }];
       }

       if (error) {
           NSLog(@"Error creating album: %@", error);
           handler(nil, error);
       }
   };

   // Set the success and failure blocks.
   [inv setArgument:&firstBlock atIndex:2];
   [inv setArgument:&secondBlock atIndex:3];

   [inv invoke];

}
else {   
   // code that always creates an album on iOS 7.x.x but fails
   // in certain situations such as if album has been deleted
   // previously on iOS 8...x. .              
   [assetsLib addAssetsGroupAlbumWithName:albumName
       resultBlock:^(ALAssetsGroup *group) {
       handler(group, nil);
   } failureBlock:^(NSError *error) {
       NSLog( @"Failed to create album: %@", albumName);
       handler(nil, error);
   }];
}