ios - 为什么从 MPMediaPicker (iOS) 返回 (null)

Question

我正在编程让 iPhone 音乐库显示，用户选择一首歌曲，然后这首歌的标题反射(reflect)在 UILabel 中。要是这么简单就好了!我已经尝试将 MPMediaItem 放入 NSString 中，然后将 UILabel 反射(reflect)出来，但我只是得到 (null) 返回!

- (IBAction)showMediaPicker:(id)sender {
    MPMediaPickerController *mediaPicker = [[MPMediaPickerController alloc] initWithMediaTypes: MPMediaTypeAny];

    mediaPicker.delegate = self;
    //mediaPicker.allowsPickingMultipleItems = YES;
    mediaPicker.prompt = @"Select Your Favourite Song!";

    [self presentModalViewController:mediaPicker animated:YES];
}

- (void) mediaPicker: (MPMediaPickerController *) mediaPicker didPickMediaItems: (MPMediaItem *) mediaItemCollection {

    NSString *titleString = [mediaItemCollection valueForProperty:MPMediaItemPropertyTitle];
    titleLabel.text = [NSString stringWithFormat:@"Title: %@",titleString];


    [self dismissModalViewControllerAnimated: YES];
}

提前致谢

Answer 1

您正在尝试获取 mediaItemCollection 的标题。您需要像这样获取单独的歌曲名称:

MPMediaItem *selectedSong = [mediaItemCollection items] objectAtIndex:0];
NSString *titleString = [selectedSong valueForProperty:MPMediaItemPropertyTitle];

另外，您的 MPMediaPickerControllerDelegate 的委托(delegate)设置有误:

应该是:

- (void)mediaPicker:(MPMediaPickerController *)mediaPicker didPickMediaItems:(MPMediaItemCollection *)mediaItemCollection

-您将 MPMediaItemCollection 作为 MPMediaItem