褪色和褪色標籤不定式用單獨的`文本'

Question

我在xCode中有一個標籤，我希望無限地淡入一個詞，然後當前時間。

我已經看過網上，可以找到一個淡入淡出，但對斯威夫特新來的，所以我努力適應這個我的需要。

任何幫助將是驚人的，謝謝！

Answer 1

這裏是如何做到這一點的例子：

@IBOutlet weak var label: UILabel! 

@IBAction func fade_out(sender: AnyObject) { 
    fade(label) 
} 

@IBAction func reset(sender: AnyObject) { 
    label.text = "label" 
} 

func fade(label : UILabel) { 
    UIView.animateWithDuration(1.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseOut, animations: { 
     label.alpha = 0.0 
    }, completion: nil) 

    UIView.animateWithDuration(2.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseIn, animations: { 
     label.alpha = 1.0 
     label.text = String(NSDate()) 
    }, completion: nil) 
} 

我要做的就是，我第一次淡出標籤與UIViewAnimationOptions.CurveEaseOut，然後用今天的日期與UIViewAnimationOptions.CurveEaseIn再次消失進去。

Here是我爲您創建的測試項目，以便您可以看到我是如何完成的。

編輯
要做到這一點無窮大，你可以像下面這樣做並沒有一個按鈕

var timer = NSTimer() 
var b = false 

override func viewDidLoad() { 
    super.viewDidLoad() 
    self.timer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: #selector(ViewController.fade), userInfo: nil, repeats: true) 
} 

func fade() { 
     if b{ 
      UIView.animateWithDuration(1.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseOut, animations: { 
       self.label.alpha = 0.0 
       self.label.text = "Label" 
       }, completion: nil) 

      UIView.animateWithDuration(1.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseIn, animations: { 
       self.label.alpha = 1.0 
       self.label.text = String(NSDate()) 
       }, completion: nil) 

      b = false 
     } 
     else{ 
      UIView.animateWithDuration(1.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseOut, animations: { 
       self.label.alpha = 0.0 
       self.label.text = String(NSDate()) 
       }, completion: nil) 

      UIView.animateWithDuration(1.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseIn, animations: { 
       self.label.alpha = 1.0 
       self.label.text = "Label" 
       }, completion: nil) 

      b = true 
     } 

    } 

Answer 2

一個更優雅的方式將是使用CAAnimation - >

class YourClass: UIViewController , ..{ 

    @IBOutlet weak var fadingLabel: UILabel! 
    var a = true 


    override func viewDidLoad() { 
      super.viewDidLoad() 


       NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: #selector(ViewController.swapText), userInfo: nil, repeats: true) 
       let anim : CABasicAnimation = CABasicAnimation(keyPath: "opacity") 
       anim.fromValue = 1 
       anim.toValue = 0 
       anim.duration = 0.5 
       anim.autoreverses = true 
       anim.repeatCount = Float.infinity 
       fadingLabel.layer.addAnimation(anim, forKey: "flashOpacity") 


    } 


    func swapText(){ 

      if a == true{ 

       fadingLabel.text = String(NSDate()) 
       a = false 
      }else{ 

       fadingLabel.text = String("My Text") 
       a = true 
      } 

    } 


} 

你現在要做的就是相應地操縱anim.duration和timeInterval在NSTimer（）中......