当我移动第一个 UIImageView 的视图光标时，我使用 UIPanGestureRecognizer 输出点 rgb 的颜色。使用这种颜色，我必须在第二个 uiview 中创建一个渐变，从起始颜色的左侧开始，到白色的右侧。我注意到在计算第一个 rgb 后，第二个 UIView 的 backgroundColor 的颜色被纠正，但是在移动第一个 UIView 的光标并在 rgb 中更改颜色后，第二个 uiview 的 backgroundColor 保持不变。
@objc func wasDragged(gestureRecognizer: UIPanGestureRecognizer) {
if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {
let translation = gestureRecognizer.translation(in: self.view)
gestureRecognizer.view!.center = CGPoint(x: gestureRecognizer.view!.center.x + translation.x, y: gestureRecognizer.view!.center.y + translation.y)
gestureRecognizer.setTranslation(CGPoint.zero, in: self.view)
let color = self.imageView.getPixelColorAt(point: gestureRecognizer.view!.center)
// color is correct
UIView.animate(withDuration: 1, delay: 0.0, options:[.repeat, .autoreverse], animations: {
self.gradientview.backgroundColor = UIColor.clear
self.gradientview.gradientBackground(from: color, to: UIColor.white, direction: GradientDirection.leftToRight)
// color is correct only first time, after remains unchanged
}, completion:nil)
}
}
在扩展中
我从这个示例开始创建渐变 以 编程方式创建具有颜色渐变的 UIView
enum GradientDirection {
case leftToRight
case rightToLeft
case topToBottom
case bottomToTop
}
extension UIView {
func gradientBackground(from color1: UIColor, to color2: UIColor, direction: GradientDirection) {
let gradient = CAGradientLayer()
gradient.frame = self.bounds
gradient.colors = [color1.cgColor, color2.cgColor]
switch direction {
case .leftToRight:
gradient.startPoint = CGPoint(x: 0.0, y: 0.5)
gradient.endPoint = CGPoint(x: 1.0, y: 0.5)
case .rightToLeft:
gradient.startPoint = CGPoint(x: 1.0, y: 0.5)
gradient.endPoint = CGPoint(x: 0.0, y: 0.5)
case .bottomToTop:
gradient.startPoint = CGPoint(x: 0.5, y: 1.0)
gradient.endPoint = CGPoint(x: 0.5, y: 0.0)
default:
break
}
self.layer.insertSublayer(gradient, at: 0)
}
}