单击按钮更改背景图像

Question

我可以这样在viewDidLoad函数上更改背景图片：

    let myBackgroundImage = UIImageView (frame: UIScreen.main.bounds)
    myBackgroundImage.image = UIImage(named: "wallpaper-1-iphone-8-plus.png")
    myBackgroundImage.contentMode = UIViewContentMode.scaleAspectFill
    self.view.insertSubview(myBackgroundImage, at: 0)

我想通过按钮单击执行相同的操作，如下所示：

    @IBAction func flip4btn5(_ sender: Any)
{
    let myBackgroundImage = UIImageView (frame: UIScreen.main.bounds)
    myBackgroundImage.image = UIImage(named: "wallpaper-2-iphone-8-plus.png")
    myBackgroundImage.contentMode = UIViewContentMode.scaleAspectFill
    self.view.insertSubview(myBackgroundImage, at: 0)
}

但它不会更改背景图片。 为什么呢 你怎么看 ？
我正在使用Swift 4.1。

Answer 1

不要创建新图像。 只需像这样在按钮操作中更改第一个UIImage的图片即可：

myBackgroundImage.image = UIImage(named: "wallpaper-2-iphone-8-plus.png")

Answer 2

每次要更改背景图像时，不要一直添加UIImageViews。

将UIImageView放在需要的视图层次结构中，并保留对其的引用。 然后根据需要在其上设置image属性。

class ViewController: UIViewController {

   @IBOutlet weak var backgroundImageView: UIImageView!

   override func viewDidLoad() {
        super.viewDidLoad()

        backgroundImageView.image = UIImage(named: "wallpaper-1-iphone-8-plus.png")
   }

   @IBAction func flip4btn5(_ sender: Any) {
       backgroundImageView.image = UIImage(named: "wallpaper-2-iphone-8-plus.png")
   }
}

您可以在情节提要中或在viewDidLoad中设置contentMode。 更新图像后，无需保持设置。

Answer 3

let myBackgroundImage = UIImageView (frame: CGRect.zero)


override func viewDidLoad() {
    super.viewDidLoad()

    myBackgroundImage.image = UIImage(named: "wallpaper-1-iphone-8-plus.png")
    myBackgroundImage.contentMode = UIViewContentMode.scaleAspectFill
    self.view.addSubview(myBackgroundImage)

}

@IBAction func ButtonPressed(_ sender: Any) {

    myBackgroundImage.image = UIImage(named: "wallpaper-2-iphone-8-plus.png")

}

Answer 4

试试这个代码，它工作正常。

class ViewController: UIViewController {

    var myBackgroundImage = UIImageView (frame: UIScreen.main.bounds);

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        myBackgroundImage.image = UIImage(named: "wallpaper-1-iphone-8-plus.png")
        myBackgroundImage.contentMode = UIViewContentMode.scaleAspectFill
        self.view.insertSubview(myBackgroundImage, at: 0)
    }

    @IBAction func flip4btn5(_ sender: UIButton) {
        myBackgroundImage.image = UIImage(named: "wallpaper-2-iphone-8-plus.png")    
    }    
}