iOS 13：MPMediaPickerController - 内部错误/找不到请求的应用扩展

Question

看来一般MPMediaPicker在ios13（ipad air 2、iphone SE）上已经不行了

从那里复制的示例 1:1 未显示媒体选择器 https://developer.apple.com/documentation/mediaplayer/displaying_a_media_picker_from_your_app

任何提示如何恢复功能？

注 1

当像这样使用MPMediaPickerController时

    musicPickerView = [[UIView alloc] initWithFrame:fullScreenRect];
    musicPickerView.alpha = 0.0f;
    musicPicker = [[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeMusic];
    musicPicker.showsCloudItems               = false;
    musicPicker.showsItemsWithProtectedAssets = false;
    musicPicker.delegate                      = self;
    musicPicker.allowsPickingMultipleItems    = false;
    musicPicker.prompt                        = NSLocalizedString(@"Select a song", @"Select a song");
    musicPicker.view.frame                    = musicPickerView.bounds;
    [self addChildViewController:musicPicker];
    [musicPickerView addSubview:musicPicker.view];
    [self.view addSubview:musicPickerView];
    [musicPicker didMoveToParentViewController:self];
    [self fadeInMusicPicker:true];

委托根本没有被调用。不显示日志，仅显示本机警报。

我得到了这个原生替代

内部错误

找不到请求的应用扩展

[取消]

注2

这似乎是该设备上未安装苹果音乐应用程序的问题。有人知道确定是否安装了苹果音乐应用的可靠方法吗？

Answer 1

似乎必须在该设备上安装来自苹果的Music 应用程序。仍然不是 100% 可重现，但安装了该应用后，我再也没有看到过这个问题。

Answer 2

您是否在 info.plist 中设置了媒体库的权限？ NSAppleMusicUsageDescription

Answer 3

来自 iOS 13 MPMediaPicker 需要用户授权，这与早期的 iO​​S 版本不同。因此，您需要先处理身份验证，然后在用户授予权限时显示选择器。你的代码如下，

MPMediaLibraryAuthorizationStatus authorizationStatus = MPMediaLibrary.authorizationStatus;

    switch (authorizationStatus)
    {
        case MPMediaLibraryAuthorizationStatusAuthorized:
        {
            [self showPickerView];
            break;
        }
        case MPMediaLibraryAuthorizationStatusNotDetermined:
        {
            // Not yet authorized - request it from the system
            [MPMediaLibrary requestAuthorization:^(MPMediaLibraryAuthorizationStatus authorizationStatus)
             {
                 if ( authorizationStatus == MPMediaLibraryAuthorizationStatusAuthorized )
                 {
                     dispatch_async(dispatch_get_main_queue(), ^{

                            [self showPickerView];

                        });
                 }
                 else
                 {
                     PLog(@"The Media Library was not authorized by the user");

                 }
             }];
            break;
        }

        case MPMediaLibraryAuthorizationStatusRestricted:
        case MPMediaLibraryAuthorizationStatusDenied:
        {
            // user has previously denied access. Ask again with our own alert that is similar to the system alert
            // then take them to the System Settings so they can turn it on for the app

            break;
        }
    }


-(void)showPickerView
{
    musicPickerView = [[UIView alloc] initWithFrame:fullScreenRect];
    musicPickerView.alpha = 0.0f;
    musicPicker = [[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeMusic];
    musicPicker.showsCloudItems               = false;
    musicPicker.showsItemsWithProtectedAssets = false;
    musicPicker.delegate                      = self;
    musicPicker.allowsPickingMultipleItems    = false;
    musicPicker.prompt                        = NSLocalizedString(@"Select a song", @"Select a song");
    musicPicker.view.frame                    = musicPickerView.bounds;
    [self addChildViewController:musicPicker];
    [musicPickerView addSubview:musicPicker.view];
    [self.view addSubview:musicPickerView];
    [musicPicker didMoveToParentViewController:self];
    [self fadeInMusicPicker:true];
}