Swift - 如何使用 UIBarButtonItem 在播放和暂停之间切换

Question

我正在我的计时器应用程序中尝试使用以下 Swift 代码来使用我拥有的相同按钮启动和暂停。但它不会切换。该按钮在 IDE 中的标识符设置为“播放”。当我运行该应用程序时，计时器会正确启动和暂停。但它没有切换按钮。它始终保持为“播放”

@IBAction func pressPausePlay(sender: AnyObject) {

    if playPause == false
    {
            timer.invalidate()
            self.playPauseButtonVar = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Play, target: self, action: "pressPausePlay")

            playPause = true
    }
    else
    {
           timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("updateTime"), userInfo: nil, repeats: true)

           self.playPauseButtonVar = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Pause, target: self, action: "pressPausePlay")

           playPause = false
    }

}

Answer 1

您可以使用此示例方案在播放和暂停之间切换，用于按钮标题、图像、导航栏、工具栏

import UIKit
import AVFoundation


class ViewController: UIViewController {

      var myPlayer = AVAudioPlayer()


    @IBOutlet var myNaviBar: UINavigationBar! //OUTLET TO NAVIGATION BAR IMPORTANT TO WORK WITH ITS BARBUTTON ITEMS

    @IBOutlet var myToolBar: UIToolbar!


//**************START :Bottom LEFT TOOLBAR Bar Button Item***********/
    @IBAction func toolBarItemPlay(sender: AnyObject) {

        myToolBar.setItems([UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Pause, target: self, action: "toolBarItemPause:")], animated: true)
        myPlayer.play()
    }


    @IBAction func toolBarItemPause(sender: AnyObject) {

        myToolBar.setItems([UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Play, target: self, action: "toolBarItemPlay:")], animated: true)
        myPlayer.pause()
    }
//**************END :Bottom LEFT TOOLBAR Bar Button Item***********/




//**************START :Top LEFT Naivation Bar Button Item***********/

    @IBAction func leftNavgationbarPlay(sender: UIBarButtonItem) {
        myNaviBar.topItem?.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .Pause, target: self, action: "leftNavigationbarPause:")
        myPlayer.play()
    }

    //no need of control drag to this one below because we are calling from the above leftNavgationbarPlay's Selector/action
    @IBAction func leftNavigationbarPause(sender : UIBarButtonItem) {
        myNaviBar.topItem?.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .Play, target: self, action: "leftNavgationbarPlay:")
        myPlayer.pause()
    }
//**************END :Top LEFT Naivation Bar Button Item***********/




//**************START :Top Right Naivation Bar Button Item***********/
    @IBAction func naviPlay(sender: UIBarButtonItem) {
        //change the topright navigation bar item from SystemItem Play '>' to systemitem pause '||'
        //  here I am assigning the top left item Play to Bar button item Pause

        /* ACTION SELECTOR IMPORTANT. IT MUST CALL THE IB ACTION FUNCTION OF PAUSE AND VICEVERSA, WITH ":" */
        myNaviBar.topItem?.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Pause, target: self, action: "naviPause:")
        myPlayer.play()
    }

    @IBAction func naviPause(sender: UIBarButtonItem) {
    myNaviBar.topItem?.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Play, target: self, action: "naviPlay:")
      myPlayer.pause()
    }
//**************END : Top Right Naivation Bar Button Item***********/





//************START :BUTTON IMAGE CHANGE - ">"to "||"************//

    @IBAction func imagePlayButton(sender: UIButton) {
        let chkImage = sender.currentImage!
        if chkImage == UIImage(named: "play.png"){


            sender.setImage(UIImage(named: "pause.png"), forState: .Normal)

            myPlayer.play()
        } else {
            sender.setImage(UIImage(named: "play.png"), forState: .Normal)
            myPlayer.pause()
        }

    }

//************END :BUTTON IMAGE CHANGE - ">"to "||"************//






//************START BUTTON TITLE CHANGE - PLAY to PAUSE************//

    @IBAction func playButton(sender: UIButton) {
        let chkTitle = sender.currentTitle
        if chkTitle == "Play" {
            sender.setTitle("Pause", forState: .Normal)
            myPlayer.play()
        } else {
            sender.setTitle("Play", forState: .Normal)
            myPlayer.pause()
        }

    }

//************END BUTTON TITLE CHANGE - PLAY to PAUSE************//




    @IBAction func naviStop(sender: UIBarButtonItem) {

        myPlayer.stop()
        myPlayer.currentTime = 0

    }

    @IBOutlet var sliderUI: UISlider!


    @IBAction func mySlider(sender: UISlider) {


        myPlayer.volume = sliderUI.value
    }




    override func viewDidLoad() {
        super.viewDidLoad()


        let audioFilePath = NSBundle.mainBundle().pathForResource("ARRehman", ofType: "mp3")

        //need NSURL from string

        do {
            myPlayer = try AVAudioPlayer(contentsOfURL: NSURL(fileURLWithPath: audioFilePath!))

        }
        catch {
            print("Some error")

        }

    }

}