使用ALAssetLibrary保存到相册时失败

Question

我试图保存一些图像，我生成了一个专辑使用ALAssetLibrary使用ALAssetsLibrary+CustomPhotoAlbum由马林托多罗夫。然而，我大多数时候都是随机失败的。

  // Get the asset library instance.
  ALAssetsLibrary *library = [ALAssetLibraryManager defaultAssetsLibrary];
  [self.imageModels enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
    // Sidenote: Trying to use an image that I have locally in my image assets fails as well.
    // UIImage *image = [UIImage imageNamed:@"Background-light-png.png"];
    UIImage *image = [UIImage imageWithContentsOfFile:[obj valueForKey:@"imagePath"]];
    [_imagesToShare addObject:image];
    if (image){
        [library saveImage:image toAlbum:@"My Album" completion:^(NSURL assetURL, NSError error) {
            NSLog(@"Success");
        } failure:^(NSError *error) {
            NSLog(@"Failed %@", error.description);
        }];
    }
}];

在failure块中，如果我添加以下代码，我可以看到图像被保存到相机滚筒中。

UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

我得到的错误是

Failed: Error Domain=LIB_ALAssetsLibrary_CustomPhotoAlbum Code=0 "ALAssetsGroup failed to add asset." UserInfo=0x171277c80 {NSLocalizedDescription=ALAssetsGroup failed to add asset.}

获取资产库的代码

+ (ALAssetsLibrary *)defaultAssetsLibrary {
   static dispatch_once_t pred = 0;
   static ALAssetsLibrary *library = nil;
   dispatch_once(&pred, ^{
        library = [[ALAssetsLibrary alloc] init];
   });
   return library;
}

我搜索了很多，但在这个话题上找不到多少。我的方法是通过单击按钮调用的，不应该同时发生其他写操作。我在网上发现的唯一信息是，您应该保留相同的ALAssetLibrary实例，这是我使用singleton类完成的。

Answer 1

以下是我如何使用资产库来保存图像：

 ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library writeImageToSavedPhotosAlbum:((UIImage *)[info objectForKey:UIImagePickerControllerEditedImage]).CGImage
                             metadata:[info objectForKey:UIImagePickerControllerMediaMetadata]
                      completionBlock:^(NSURL *assetURL, NSError *error) {
                          NSLog(@"assetURL %@", assetURL);
                            imageURL=[assetURL absoluteString];

                          [[NSUserDefaults standardUserDefaults] setObject:imageURL forKey:@"imageurl"]; //for reference of the path

                      }];