Question

我的UITableView中有多个部分，我想更改我的视图   背景色为渐变色，平滑过渡时   滚动tableView。

当新的部分进入tableView更改视图背景颜色时   顺利进行。

我如何实现这种动画。

我的代码如下所示，用于更改背景颜色但不顺畅

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

您可以使用此代码平滑地更改视图渐变颜色 -

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)
}

使用平滑动画更改视图背景渐变颜色，同时在tableView中滚动多个部分

2 个答案: