我如何使背景连续闪烁或闪烁，直到按钮再次按下，然后它会闪烁或闪烁2个新的随机颜色

Question

我怎样才能使背景色在每次按下按钮时连续闪现2个新颜色？现在它只显示两种颜色，但它们不会连续闪烁或闪烁。

import UIKit

class ViewController: UIViewController {
    
    let colors: [UIColor] = [
        .systemYellow,
        .systemGreen,
        .systemPurple,
        .systemPink,
        .systemRed,
        .systemBlue,
        .systemOrange,
        .black,.gray
    ]
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .clear
    }
    
    @IBAction func didTapButton() {
        
        UIView.animate(withDuration: 1/2, delay: 0, options: .curveEaseOut, animations: {
            self.view.backgroundColor = self.colors.randomElement()
        }, completion: { finished in
            print("another animation! - 1")
            UIView.animate(withDuration: 1/2, delay: 0, options: .curveEaseOut, animations: {
                self.view.backgroundColor = self.colors.randomElement()
            }, completion: { finished in
                print("another animation! - 2")
            })
        })
    }
}

Answer 1

像这样的？

可以使用[.repeat,.autoreverse]选项重复和反转彩色动画。

然后，由于按钮是您正在动画的视图的子视图（在动画过程中，通常禁用视图及其子视图的用户交互），您可以添加.AllowUserInteraction选项以允许再次按下按钮。

@IBAction func didTapButton() {
    let color1 = self.colors.randomElement()
    let color2 = self.colors.randomElement()
    
    self.view.layer.removeAllAnimations()
    self.view.backgroundColor = color1 /// set to color1
    UIView.animate(withDuration: 1, delay: 0, options: [.repeat, .autoreverse, .allowUserInteraction]) {
        self.view.backgroundColor = color2 /// now animate to color2, reverse, then repeat
    }
}