將圖像保存到照片庫並獲取保存的圖像的URL

Question

我試圖將圖像從相機保存到照片庫，然後存儲保存的圖像的URL。我的代碼：

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

ALAssetsLibrary *library = [[ALAssetsLibrary alloc]init]; 
[library writeImageToSavedPhotosAlbum:(__bridge CGImageRef)([info objectForKey:UIImagePickerControllerOriginalImage]) 
          orientation:ALAssetOrientationUp completionBlock:^(NSURL *assetURL, NSError *error) { 
           if(error == nil) { 
            _myImageUrl = [NSString stringWithFormat:@"%@",assetURL]; 
            NSLog(@"%@",assetURL); 
           } else NSLog(@"%@",error); 
          }]; 

[picker dismissViewControllerAnimated:YES completion:nil];} 

我的問題是，assetUrl始終爲NULL。有任何想法嗎？ 謝謝！

Answer 1

最後，在閱讀更多內容後，我發現答案：函數的第一個參數是CGImageRef類型，而(__bridge CGImageRef)不符合我的預期;但如果我打電話UIImage對象的CGImage方法，它的工作原理。正確的方法是：

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

    ALAssetsLibrary *library = [[ALAssetsLibrary alloc]init]; 
    CGImageRef image = [[info objectForKey:UIImagePickerControllerOriginalImage] CGImage]; 
    [library writeImageToSavedPhotosAlbum:image 
           orientation:ALAssetOrientationUp 
          completionBlock:^(NSURL *assetURL, NSError *error) { 
            if(error == nil) { 
             _myImageUrl = [NSString stringWithFormat:@"%@",assetURL]; 
             NSLog(@"%@",assetURL); 
            } else NSLog(@"%@",error); 
           }]; 

    self.toDoImage.image = [info objectForKey:UIImagePickerControllerOriginalImage]; 
    [picker dismissViewControllerAnimated:YES completion:nil]; 
}