ios - 使用照片框架将图像保存到照片库

Question

每次尝试使用照片框架保存图像时，我的应用程序都会崩溃。

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{

      _mChangeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];

      [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{

      _mChangeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];

      } completionHandler:^(BOOL success, NSError *error) {

          if (success) {

              PHObjectPlaceholder *assetPlaceholder = _mChangeRequest.placeholderForCreatedAsset;
          }
          else {

             NSLog(@"write error : %@",error);
          }
    }];
}

crash : NSInternalInconsistencyException', reason: 'This method can only be called from inside of -[PHPhotoLibrary performChanges:completionHandler:] or -[PHPhotoLibrary performChangesAndWait:error:]'

Answer 1

您需要做的就是触发创建请求。如错误所述，您只能在 performChanges block 内访问更改请求。

因此，要保存图像，您需要执行以下操作:

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    [PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];
} completionHandler:^(BOOL success, NSError *error) {
    if (success) {
         NSLog(@"Success");
    }
    else {
        NSLog(@"write error : %@",error);
    }
}];

如果您需要对新创建的 Assets 的占位符执行某些操作，您可以在同一个 performChanges block 中访问它:

PHAssetChangeRequest *changeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];
PHObjectPlaceholder *assetPlaceholder = changeRequest.placeholderForCreatedAsset;