单击按钮更改背景图像

Question

我可以像这样更改 viewDidLoad 函数的背景图片：

    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)

我想像这样通过单击按钮执行相同的操作：

    @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像。为什么？你怎么看？
我正在使用 Swift 4.1.

Answer 1

不要在每次要更改背景图像时都添加 UIImageView。

在视图层次结构中需要它的地方放置一个 UIImageView 并保留对它的引用。然后根据需要在上面设置图片属性。

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")
   }
}

您可以在故事板或viewDidLoad 中设置contentMode。更新图像后无需继续设置。

Answer 2

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 3

不要创建新图像。只需像这样更改按钮操作中第一个 UIImage 的图片：

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")    
    }    
}

单击按钮更改背景图像

Change background image with button click

uiimageview

ios

swift