ios - 如何快速更改 Controller View 某些部分的颜色？

Question

我创建了一个自定义 UIView。我正在使用下面的代码将它的一部分颜色设置为其他颜色。

import Foundation

class BottomView:UIView {

    override func draw(_ rect: CGRect) {
        self.fillColor(with: .gray, width: 20)
    }

    func fillColor(with color:UIColor,width:CGFloat) {

        let topRect = CGRect(x:0, y:0, width : width, height: self.bounds.height);
        color.setFill()
        UIRectFill(topRect)

    }

}

现在我的 View 有一些颜色的初始部分，因为灰色和其余颜色不同。现在从 Controller ，如果我尝试将它的颜色更改为绿色，它不会从开始位置更改。它的颜色在初始颜色后发生了变化。

请告诉我如何将背景颜色完全设置为绿色。

Answer 1

您可以在底部 View 上使用setNeedsDisplay 并在设置backgroundColor 时重绘它。

setNeedsDisplay()

Marks the receiver’s entire bounds rectangle as needing to be redrawn.

You can use this method or the setNeedsDisplay(_:) to notify the system that your view’s contents need to be redrawn. This method makes a note of the request and returns immediately. The view is not actually redrawn until the next drawing cycle, at which point all invalidated views are updated.

示例:

<强>1。 BottomView 类

class BottomView:UIView
{
    var showGray = true

    override func draw(_ rect: CGRect)
    {
        if showGray
        {
            self.fillColor(with: .gray, width: 20)
        }
    }

    func fillColor(with color:UIColor,width:CGFloat)
    {
        let topRect = CGRect(x:0, y:0, width : width, height: self.bounds.height);
        color.setFill()
        UIRectFill(topRect)
    }
}

<强>2。在你的 UIViewController

self.bottomView.showGray = false
self.bottomView.setNeedsDisplay()
self.bottomView.backgroundColor = .green