ios - Swift 图像按钮上的淡入淡出(过渡效果)

Question

我有一个带有默认状态和高亮状态的 UIButton，所以当它处于默认状态时它显示 image.png，当被点击时它显示 imageOn.png。

这与图像之间唯一的变化是背景颜色。

我无法做的事情是在单击按钮时在这两个图像之间进行淡入淡出，以进行精美的背景颜色更改。我正在使用 Swift。

Answer 1

好吧，我现在没有时间测试这个，但我认为你的代码应该看起来像这样。

override func viewDidLoad() {

let normalImage = UIImage(named: "image.png") as UIImage!
let selectedImage = UIImage(named: "imageOn.png") as UIImage!

var mybutton:UIButton  = UIButton.buttonWithType(UIButtonType.System) as UIButton

mybutton.setTitle("Your title", forState: UIControlState.Normal)
mybutton.frame = CGRectMake(0, 0, 100, 44)

self.view.addSubview(button as UIView)
//set normal image 
mybutton.setImage(normalImage, forState: UIControlState.Normal)
//set highlighted image 
mybutton.setImage(selectedImage, forState: UIControlState.Selected)

mybutton.addTarget(self, action: "buttonClicked:", forControlEvents: UIControlEvents.TouchUpInside)

}

func buttonClicked(sender:UIButton)
{

if (sender.selected)  { 
    UIView.animateWithDuration(1.5, animations: {
        self.normalImage.alpha = 1.0
        self.selectedImage.alpha = 0.0
    sender.selected = !sender.selected; 
}
else{  
    UIView.animateWithDuration(1.5, animations: {
        self.normalImage.alpha = 0.0
        self.selectedImage.alpha = 1.0  
}

}

祝你好运!