Ios 如何在普通UIView（非UIImage）上获得多重混合模式

我的iPad应用程序中有一张图片，我基本上想在上面放置一个滤色器。对于这一点，我有一个彩色的UIView，它被遮罩成一个特定的形状，我把它覆盖在图像上。因为调整alpha并没有给我想要的效果，所以我想使用混合模式

据我所知，您只能在图像上使用混合模式，而不能在普通视图上使用混合模式。视图的颜色是动态的，所以我不能只使用图片

我还尝试将视图栅格化为一幅图像，但结果都是像素和奇数之类的，但可能是我做错了什么

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因此，基本问题是：是否可以将混合模式应用于视图？还是我应该采取完全不同的方法来达到相同的目标？

看看CALayer的合成过滤器文档：

在颜色覆盖视图中，您可以将

view.layer.compositingFilter

设置为a，以实现与其后面内容的混合。下面是一些应用了多重混合模式的示例代码（用您自己的图像替换

UIImage（名为：“”）

进行测试）

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iOS 13，Swift 5

关键是在相应的CALayer上设置

compositingFilter

属性（顶部的一个-它与后面的任何内容混合）。颜色混合在UIView或Calayer之间工作。你可以在这里找到混合模式。要使用过滤器，只需删除

CI

&名称的第一个字母小写（例如

CIDivideBlendMode

变为

divideBlendMode

）。下面是一些游乐场代码来说明：

import UIKit
import PlaygroundSupport

let view = UIView(frame: CGRect(x: 0, y: 0, width: 500, height: 900))
PlaygroundPage.current.liveView = view


let heightIncrement = view.frame.height / 13
let widthIncrement = view.frame.width / 7


// TOP EXAMPLE (UIViews)

let backgroundView = UIView(frame: CGRect(x: widthIncrement * 2,
                                          y: heightIncrement,
                                          width: widthIncrement * 3,
                                          height: heightIncrement * 5))
backgroundView.backgroundColor = .black
view.addSubview(backgroundView)

let overlayView1 = UIView(frame: CGRect(x: widthIncrement,
                                        y: heightIncrement * 2,
                                        width: widthIncrement * 5,
                                        height: heightIncrement))
overlayView1.backgroundColor = UIColor.yellow.withAlphaComponent(0.3)
overlayView1.layer.compositingFilter = "darkenBlendMode"
view.addSubview(overlayView1)

let overlayView2 = UIView(frame: CGRect(x: widthIncrement,
                                        y: heightIncrement * 4,
                                        width: widthIncrement * 5,
                                        height: heightIncrement))
overlayView2.backgroundColor = UIColor.yellow.withAlphaComponent(0.3)
overlayView2.layer.compositingFilter = "divideBlendMode"
view.addSubview(overlayView2)




// BOTTOM EXAMPLE (CALayers)

let backgroundLayer = CALayer()
backgroundLayer.frame = CGRect(x: widthIncrement * 2,
                               y: heightIncrement * 7,
                               width: widthIncrement * 3,
                               height: heightIncrement * 5)
backgroundLayer.backgroundColor = UIColor.black.cgColor
view.layer.addSublayer(backgroundLayer)

let overlayLayer1 = CALayer()
overlayLayer1.frame = CGRect(x: widthIncrement,
                             y: heightIncrement * 8,
                             width: widthIncrement * 5,
                             height: heightIncrement)
overlayLayer1.backgroundColor = UIColor.yellow.withAlphaComponent(0.3).cgColor
overlayLayer1.compositingFilter = "darkenBlendMode"
view.layer.addSublayer(overlayLayer1)

let overlayLayer2 = CALayer()
overlayLayer2.frame = CGRect(x: widthIncrement,
                             y: heightIncrement * 10,
                             width: widthIncrement * 5,
                             height: heightIncrement)
overlayLayer2.backgroundColor = UIColor.yellow.withAlphaComponent(0.3).cgColor
overlayLayer2.compositingFilter = "divideBlendMode"
view.layer.addSublayer(overlayLayer2)

结果如下所示：

我证实了同样的代码在iOS中也能工作。以下是视图控制器代码：

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)


        let heightIncrement = view.frame.height / 13
        let widthIncrement = view.frame.width / 7


        // TOP EXAMPLE (UIViews)

        let backgroundView = UIView(frame: CGRect(x: widthIncrement * 2,
                                                  y: heightIncrement,
                                                  width: widthIncrement * 3,
                                                  height: heightIncrement * 5))
        backgroundView.backgroundColor = .black
        view.addSubview(backgroundView)

        let overlayView1 = UIView(frame: CGRect(x: widthIncrement,
                                                y: heightIncrement * 2,
                                                width: widthIncrement * 5,
                                                height: heightIncrement))
        overlayView1.backgroundColor = UIColor.yellow.withAlphaComponent(0.3)
        overlayView1.layer.compositingFilter = "darkenBlendMode"
        view.addSubview(overlayView1)

        let overlayView2 = UIView(frame: CGRect(x: widthIncrement,
                                                y: heightIncrement * 4,
                                                width: widthIncrement * 5,
                                                height: heightIncrement))
        overlayView2.backgroundColor = UIColor.yellow.withAlphaComponent(0.3)
        overlayView2.layer.compositingFilter = "divideBlendMode"
        view.addSubview(overlayView2)




        // BOTTOM EXAMPLE (CALayers)

        let backgroundLayer = CALayer()
        backgroundLayer.frame = CGRect(x: widthIncrement * 2,
                                       y: heightIncrement * 7,
                                       width: widthIncrement * 3,
                                       height: heightIncrement * 5)
        backgroundLayer.backgroundColor = UIColor.black.cgColor
        view.layer.addSublayer(backgroundLayer)

        let overlayLayer1 = CALayer()
        overlayLayer1.frame = CGRect(x: widthIncrement,
                                     y: heightIncrement * 8,
                                     width: widthIncrement * 5,
                                     height: heightIncrement)
        overlayLayer1.backgroundColor = UIColor.yellow.withAlphaComponent(0.3).cgColor
        overlayLayer1.compositingFilter = "darkenBlendMode"
        view.layer.addSublayer(overlayLayer1)

        let overlayLayer2 = CALayer()
        overlayLayer2.frame = CGRect(x: widthIncrement,
                                     y: heightIncrement * 10,
                                     width: widthIncrement * 5,
                                     height: heightIncrement)
        overlayLayer2.backgroundColor = UIColor.yellow.withAlphaComponent(0.3).cgColor
        overlayLayer2.compositingFilter = "divideBlendMode"
        view.layer.addSublayer(overlayLayer2)
    }
}

下面是模拟器中的结果：

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和？1） 该链接是关于使用图层的。在您的回答中，您将“层”替换为“视图”，它当然不起作用。2） 即使我使用了他们的建议-从您的链接：“iOS中的层不支持此属性”。。。DownvotedUIViews有图层我刚刚在iPhone 6上运行了一个测试应用程序，它使用了

overlay.layer.compositingFilter=“multiplyBlendMode”

，效果非常好！我看不到iOS支持问题。此解决方案不再有效！在iOS 13中，设置CALayer.compositingFilter是不可操作的。还有其他人遇到此问题吗？（2019年9月）谢谢！请您解释一下，您是如何发现可以在compositingFilter属性上使用像“divideBlendMode”这样的字符串，而不是像“CIDivideBlendMode”这样的字符串的？在文档中有

compositingFilter:Any？

，我不清楚如何使用它

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)


        let heightIncrement = view.frame.height / 13
        let widthIncrement = view.frame.width / 7


        // TOP EXAMPLE (UIViews)

        let backgroundView = UIView(frame: CGRect(x: widthIncrement * 2,
                                                  y: heightIncrement,
                                                  width: widthIncrement * 3,
                                                  height: heightIncrement * 5))
        backgroundView.backgroundColor = .black
        view.addSubview(backgroundView)

        let overlayView1 = UIView(frame: CGRect(x: widthIncrement,
                                                y: heightIncrement * 2,
                                                width: widthIncrement * 5,
                                                height: heightIncrement))
        overlayView1.backgroundColor = UIColor.yellow.withAlphaComponent(0.3)
        overlayView1.layer.compositingFilter = "darkenBlendMode"
        view.addSubview(overlayView1)

        let overlayView2 = UIView(frame: CGRect(x: widthIncrement,
                                                y: heightIncrement * 4,
                                                width: widthIncrement * 5,
                                                height: heightIncrement))
        overlayView2.backgroundColor = UIColor.yellow.withAlphaComponent(0.3)
        overlayView2.layer.compositingFilter = "divideBlendMode"
        view.addSubview(overlayView2)




        // BOTTOM EXAMPLE (CALayers)

        let backgroundLayer = CALayer()
        backgroundLayer.frame = CGRect(x: widthIncrement * 2,
                                       y: heightIncrement * 7,
                                       width: widthIncrement * 3,
                                       height: heightIncrement * 5)
        backgroundLayer.backgroundColor = UIColor.black.cgColor
        view.layer.addSublayer(backgroundLayer)

        let overlayLayer1 = CALayer()
        overlayLayer1.frame = CGRect(x: widthIncrement,
                                     y: heightIncrement * 8,
                                     width: widthIncrement * 5,
                                     height: heightIncrement)
        overlayLayer1.backgroundColor = UIColor.yellow.withAlphaComponent(0.3).cgColor
        overlayLayer1.compositingFilter = "darkenBlendMode"
        view.layer.addSublayer(overlayLayer1)

        let overlayLayer2 = CALayer()
        overlayLayer2.frame = CGRect(x: widthIncrement,
                                     y: heightIncrement * 10,
                                     width: widthIncrement * 5,
                                     height: heightIncrement)
        overlayLayer2.backgroundColor = UIColor.yellow.withAlphaComponent(0.3).cgColor
        overlayLayer2.compositingFilter = "divideBlendMode"
        view.layer.addSublayer(overlayLayer2)
    }
}