UIBarButton沒有改變

Question

@IBOutlet weak var playStopButton: UIBarButtonItem!
var playStopArray = [UIBarButtonSystemItem.Pause, UIBarButtonSystemItem.Play]
var index = 0

@IBOutlet weak var image: UIImageView!
@IBAction func playButton(sender: UIBarButtonItem) {
    println("pressed")
    playStopButton = UIBarButtonItem(barButtonSystemItem: playStopArray[index], target: self, action: "startMusic:")
    println("here")
    if index == 0 {
        index = 1
    }
    else {
        index = 0
    }
}
func startMusic() {
    println("test")
}

我希望條形按鈕更改為暫停符號，但是沒有運氣。 它同時打印“按下”和“此處”，但“測試”不起作用。 為什么圖像沒有變化？

Answer 1

您的方法是錯誤的。

在下一行中，
playStopButton = UIBarButtonItem(barButtonSystemItem: playStopArray[index], target: self, action: "startMusic:")
您實際上是在創建UIBarButtonItem的新實例。 該按鈕實際上並未添加到視圖中。 而不是通過Interface Builder添加UIBarButtonItem 。 您可以以編程方式創建它。

閱讀此問題以獲取更多信息。 在UIBarButtonSystemItemPlay和UIBarButtonSystemItemPause之間切換

var playButton:UIBarButtonItem!
var pauseButton:UIBarButtonItem!

func setup()
{
    playButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Play, target: self, action: "startMusic:")
    pauseButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Pause, target: self, action: "stopMusic:")
}

func startMusic:(button : UIBarButtonItem)
{
     self.navigationItem.rightBarButtonItem = pauseButton // Switch to pause.
     //Other code.
}
func stopMusic:(button : UIBarButtonItem)
{
    self.navigationItem.rightBarButtonItem = playButton// Switch to play.
    //Other code.
}

Answer 2

這是我在Swift中的方法

func configureBars() {
  isPlaying = false
  // UIToolbar
  let pickBarButtonItem = UIBarButtonItem(barButtonSystemItem: .Search,
    target: self,
    action: "pickSong")
  let playBarButtonItem = UIBarButtonItem(barButtonSystemItem: .Play,
    target: self,
    action: "playPause")
  let pauseBarButtonItem = UIBarButtonItem(barButtonSystemItem: .Pause,
    target: self,
    action: "playPause")
  let leftFlexBBI = UIBarButtonItem(barButtonSystemItem: .FlexibleSpace,
    target: nil,
    action: nil)
  let rightFlexBBI = UIBarButtonItem(barButtonSystemItem: .FlexibleSpace,
    target: nil,
    action: nil)
  playItems = [pickBarButtonItem, leftFlexBBI, playBarButtonItem, rightFlexBBI]
  pauseItems = [pickBarButtonItem, leftFlexBBI, pauseBarButtonItem, rightFlexBBI]

  toolbar.items = playItems
}

請訪問http://www.raywenderlich.com/36475/how-to-make-a-music-visualizer-in-ios ，也可以查看我的Github https://github.com/Charles-Hsu/MusicVisualizer