在具有多个部分的 tableView 中滚动时，使用流畅的动画更改视图背景渐变颜色

Question

I have multiple section in my UITableView, i want to change my View back ground color as gradient color with smooth transition while scrolling tableView.

when new section comes in tableView change view background color smoothly.

如何实现这种动画？

My Code is below for change the background color but not smoothly

func tableView(_ tableView: UITableView, willDisplayHeaderView view: UIView, forSection section: Int) {
        switch section {
        case 0:
                self.view.backgroundColor = UIColor.cyan
            break
        case 1:
               self.view.backgroundColor = UIColor.red
            break
        case 2:
               self.view.backgroundColor = UIColor.green
            break
        case 3:
               self.view.backgroundColor = UIColor.blue
            break
        case 4:
               self.view.backgroundColor = UIColor.brown
            break
        default:
              self.view.backgroundColor = UIColor.brown
            break
        }
    }

Answer 1

您可以尝试使用此代码。

func tableView(_ tableView: UITableView, willDisplayHeaderView view: 
UIView, forSection section: Int) {

    switch section {
    case 0:
        UIView.animate(withDuration: 0.5, delay: 0.0, options: [.curveEaseIn, .curveEaseOut, .allowUserInteraction], animations: {() -> Void in
            self.view.backgroundColor = UIColor.cyan.withAlphaComponent(0.4)

        })

    case 1:
        UIView.animate(withDuration: 0.5, delay: 0.0, options: [.curveEaseIn, .curveEaseOut, .allowUserInteraction], animations: {() -> Void in
            self.view.backgroundColor = UIColor.green.withAlphaComponent(0.4)

        })

    case 2:
        UIView.animate(withDuration: 0.5, delay: 0.0, options: [.curveEaseIn, .curveEaseOut, .allowUserInteraction], animations: {() -> Void in
            self.view.backgroundColor = UIColor.yellow.withAlphaComponent(0.4)

        })

    case 3:
        UIView.animate(withDuration: 0.5, delay: 0.0, options: [.curveEaseIn, .curveEaseOut, .allowUserInteraction], animations: {() -> Void in
            self.view.backgroundColor = UIColor.orange.withAlphaComponent(0.4)

        })

    case 4:
        UIView.animate(withDuration: 0.5, delay: 0.0, options: [.curveEaseIn, .curveEaseOut, .allowUserInteraction], animations: {() -> Void in
            self.view.backgroundColor = UIColor.magenta.withAlphaComponent(0.4)

        })

    default:
        self.view.backgroundColor = UIColor.brown

    }
}

Answer 2

You can change view gradient color smoothly with this code -

func tableView(_ tableView: UITableView, willDisplayHeaderView view: UIView, forSection section: Int) {
    for layer in self.view.layer.sublayers! {
        if layer .isKind(of: CAGradientLayer.self) {
            layer.removeFromSuperlayer()
        }
    }
    let gradient = CAGradientLayer()
    gradient.frame = self.view.bounds
    gradient.colors = [self.generateRandomColor().cgColor, self.generateRandomColor().cgColor]
    let anim:CABasicAnimation = CABasicAnimation.init(keyPath: "opacity")
    anim.fromValue = 0.5
    anim.toValue = 1
    anim.duration = 1.0
    gradient.add(anim, forKey: "opacity")
    self.view.layer.addSublayer(gradient)
    self.view.layoutIfNeeded()
}

func generateRandomColor() -> UIColor {
    let hue : CGFloat = CGFloat(arc4random() % 256) / 256 + 0.5
    let saturation : CGFloat = CGFloat(arc4random() % 128) / 256 + 0.5
    let brightness : CGFloat = CGFloat(arc4random() % 128) / 256 + 0.5
    return UIColor(hue: hue, saturation: saturation, brightness: brightness, alpha: 0.5)
}

在具有多个部分的 tableView 中滚动时，使用流畅的动画更改视图背景渐变颜色

Change view background gradient color with smooth animation while scrolling in tableView with multiple section

animation

gradient

tableview

ios

swift