Question

编写下面的代码/保持警告Variable 'albumArt' was written to, but never read Xcode生成的警告是一种更好的方法

在

func getCurrentlyPlayedInfo() {
  DispatchQueue.main.async {
    if let songInfo = self.mediaPlayer.nowPlayingItem {
      self.songNameLabel.text = songInfo.title ?? ""
      self.songAlbumLabel.text = songInfo.albumTitle ?? ""
      self.songArtistLabel.text = songInfo.artist ?? ""

      //This line generates the warning
      if var albumArt = self.albumArtImageView?.image {
      albumArt = songInfo.artwork?.image(at: CGSize(width: 400, height: 400)) ?? #imageLiteral(resourceName: "emptyArtworkImage")
      //

    }
  }
}

对于上下文，此功能使用当前正在播放的歌曲“标题”，“专辑”，“艺术家”和“专辑插图”来更新应用的用户界面。

Answer 1

它之所以发出警告，是因为您为一个变量albumArt分配了一个值，下面的代码不再使用警告了：

    func getCurrentlyPlayedInfo() {
      DispatchQueue.main.async {
        if let songInfo = self.mediaPlayer.nowPlayingItem {
          self.songNameLabel.text = songInfo.title ?? ""
          self.songAlbumLabel.text = songInfo.albumTitle ?? ""
          self.songArtistLabel.text = songInfo.artist ?? ""

        if let _ = self.albumArtImageView.image {
     _ = songInfo.artwork?.image(at: CGSize(width: 400, height: 400)) ?? #imageLiteral(resourceName: "emptyArtworkImage")
      //

    }
      }
    }

最适当的语法来使警告静音并使用适当的编码技术

1 个答案: