我正在尝试将渐变应用于主视图的顶部,左侧和右侧约束的视图,但由于某种原因,渐变不会覆盖应用于视图的整个宽度(请参阅图中的黄色。)
class ViewController: UIViewController {
@IBOutlet weak var myView: UIView!
override func viewDidLoad() {
super.viewDidLoad()
let gradient = CAGradientLayer()
gradient.colors = [UIColor.blue.cgColor, UIColor.white.cgColor]
gradient.startPoint = CGPoint(x:00, y:00)
gradient.endPoint = CGPoint(x:0, y:0.6)
gradient.frame = myView.bounds
myView.clipsToBounds = true
myView.layer.insertSublayer(gradient, at: 0)
}
}
我做错了什么?
答案 0 :(得分:18)
问题可能是您在viewDidLoad()
中添加了渐变图层。在viewDidLoad()
之后,视图不会设置为最终大小。
您的视图控制器可能会在您的XIB / Storyboard中设置,其屏幕尺寸与您在其上运行时不同。 (假设您已将其设置为iPhone SE大小,但您在6上运行它.6的屏幕稍微宽一点,因此图层将设置为iPhone SE的宽度,首先加载视图。然后将调整视图大小,但不会调整图层的大小。)
您应该实现UIViewController方法viewDidLayoutSubviews()
,并在该方法中调整图层的框架:
override func viewDidLayoutSubviews() {
gradientLayer.frame = self.view.bounds
}
这样,如果视图调整大小(例如,由于自动旋转),渐变图层将相应地自动调整。
正如Sulthan所指出的,默认情况下,对图层框架的更改是动画的。您应该将框架更改换成CATransaction.begin
/ CATransaction.end
并禁用操作,如下所示:
override func viewDidLayoutSubviews() {
CATransaction.begin()
CATransaction.setDisableActions(true)
gradientLayer.frame = self.view.bounds
CATransaction.commit()
}
答案 1 :(得分:1)
您的目标是让渐变跨越整个视图,您无需设置起点和终点。你已经用`
设置了它gradientLayer.frame = self.view.bounds
`
import UIKit
class ViewController: UIViewController {
@IBOutlet weak var myView: UIView!
var gradientLayer: CAGradientLayer!
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
createGradientLayer()
}
func createGradientLayer() {
gradientLayer = CAGradientLayer()
gradientLayer.frame = self.view.bounds
gradientLayer.colors = [UIColor.blueColor().CGColor, UIColor.whiteColor().CGColor]
self.view.layer.addSublayer(gradientLayer)
}
}
答案 2 :(得分:0)
您可以通过CustomClass用一行代码对其进行简化
class GradientView: UIView {
override class var layerClass: Swift.AnyClass {
return CAGradientLayer.self
}
}
// MARK: Usage
@IBOutlet weak var myView: GradientView!
guard let gradientLayer = myView.layer as? CAGradientLayer else { return }
gradient.colors = [UIColor.blue.cgColor, UIColor.white.cgColor]
gradient.startPoint = CGPoint(x: 0.0, y: 0.0)
gradient.endPoint = CGPoint(x:0, y:0.6)
答案 3 :(得分:0)
您可以将其变成UIView
。因此它将自动调整大小,并可以直接在情节提要中查看:
@IBDesignable
final class GradientView: UIView {
@IBInspectable var firstColor: UIColor = .clear { didSet { updateView() } }
@IBInspectable var secondColor: UIColor = .clear { didSet { updateView() } }
@IBInspectable var startPoint: CGPoint = CGPoint(x: 0, y: 0) { didSet { updateView() } }
@IBInspectable var endPoint: CGPoint = CGPoint(x: 1, y: 1) { didSet { updateView() } }
override class var layerClass: AnyClass { get { CAGradientLayer.self } }
override func layoutSubviews() {
super.layoutSubviews()
updateView()
layer.frame = bounds
}
private func updateView() {
let layer = self.layer as! CAGradientLayer
layer.colors = [firstColor, secondColor].map {$0.cgColor}
layer.startPoint = startPoint
layer.endPoint = endPoint
}
}