遇到Apple提供的MusicKit示例应用程序的麻烦 [英] Having trouble with MusicKit sample app provided by Apple

问题描述

我正在尝试在Xcode 9 beta 3上构建由Apple提供的Music Kit示例应用程序向Apple Music添加内容".但是，我遇到了4个类似的错误:3"play()"的歧义使用)错误和一个歧义使用'pause()'"

I am trying to build "Adding Content to Apple Music", Music Kit sample app provided by Apple, on Xcode 9 beta 3. However I am having 4 errors like this : three "Ambiguous use of 'play()’" errors and one "Ambiguous use of 'pause()’"

如果您已解决此问题，请告诉我如何解决.

Please tell me how to fix this if you already solved this problem.

func beginPlayback(itemCollection: MPMediaItemCollection) {
    musicPlayerController.setQueue(with: itemCollection)

    //Ambiguous use of 'play()’
    musicPlayerController.play()
}

func beginPlayback(itemID: String) {
    musicPlayerController.setQueue(with: [itemID])

    //Ambiguous use of 'play()’
    musicPlayerController.play()
}

// MARK: Playback Control Methods

func togglePlayPause() {
    if musicPlayerController.playbackState == .playing {

        //Ambiguous use of 'pause()’
        musicPlayerController.pause()
    } else {

        //Ambiguous use of 'play()’
        musicPlayerController.play()
    }
}

推荐答案

我在Apple开发论坛中发现了类似的问题:

I have found a similar question in the Apple's Dev Forums:

MPMusicPlayerController Swift4-玩游戏的模棱两可

根据写解决此问题的修补程序的条目，您需要在MusicPlayerManager.swift中更改此行:

According to an entry writing a fix to work around the issue, you need to change this line in MusicPlayerManager.swift:

let musicPlayerController = MPMusicPlayerController.systemMusicPlayer

(使用此代码，musicPlayerController的类型变为MPMusicPlayerController & MPSystemMusicPlayerController.)

(musicPlayerController's type becomes MPMusicPlayerController & MPSystemMusicPlayerController with this code.)

收件人:

let musicPlayerController: MPMusicPlayerController = MPMusicPlayerController.systemMusicPlayer

(musicPlayerController显式标注为MPMusicPlayerController.)

我认为这是Swift的错误，与 Apple 或 swift.org .

In my opinion this is a bug of Swift related to SE-0156 Class and Subtype existentials and you should better send a bug report to Apple or swift.org.

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