[英]Change background image with button click
我可以這樣在viewDidLoad函數上更改背景圖片:
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)
我想通過按鈕單擊執行相同的操作,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)
}
但它不會更改背景圖片。 為什么呢 你怎么看 ?
我正在使用Swift 4.1。
不要創建新圖像。 只需像這樣在按鈕操作中更改第一個UIImage的圖片即可:
myBackgroundImage.image = UIImage(named: "wallpaper-2-iphone-8-plus.png")
每次要更改背景圖像時,不要一直添加UIImageViews。
將UIImageView放在需要的視圖層次結構中,並保留對其的引用。 然后根據需要在其上設置image屬性。
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")
}
}
您可以在情節提要中或在viewDidLoad中設置contentMode。 更新圖像后,無需保持設置。
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")
}
試試這個代碼,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")
}
}
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