为什么单击按钮时这些框的颜色不会改变？ (Swift)

Question

所以我有一个名为 "cell" 的 UIView，它在 for 循环中重复，我设置了 func makeStuffHappen() ，它在按下 UIButton 时执行。该函数应该是将颜色更改为 UIView。

我做错了什么？

import UIKit
import PlaygroundSupport

// STEP 1: consts and vars

let view = UIView(frame: CGRect(x: 0, y: 0, width: 500, height: 600))
let colorButton = UIButton(frame: CGRect(x: 460, y: 560, width: 30, height: 30))
let numberOfCellsOnAxis = 6
let cellDimensions = view.frame.height / CGFloat(numberOfCellsOnAxis)
var cell = UIView()

func randomColor() -> UIColor {

    let red = CGFloat(arc4random_uniform(256))
    let green = CGFloat(arc4random_uniform(256))
    let blue = CGFloat(arc4random_uniform(256))

    return UIColor(red: red / 255, green: green / 255, blue: blue / 255, alpha: 1)
}

class takeAction : NSObject {

    var tapCount = 0


    @objc func makeStuffHappen() {

        cell.backgroundColor = randomColor()
        tapCount += 1
        print("gesture recognized, colors have changed \(tapCount) times!")

    }

}

let TakeAction = takeAction()


colorButton.addTarget( TakeAction, action: #selector(takeAction.makeStuffHappen), for: .touchUpInside)


// STEP 2: Setup repeating boxes on both x and y axis within view


for xAxis in 0...(numberOfCellsOnAxis - 1) {
    for yAxis in 0...(numberOfCellsOnAxis - 1) {

        cell = UIView()

        cell.frame = CGRect(x: CGFloat(xAxis) * cellDimensions, y: CGFloat(yAxis) * cellDimensions, width: cellDimensions, height: cellDimensions)

        cell.backgroundColor = randomColor()
        view.addSubview(cell)

    }

}

colorButton.backgroundColor = .magenta

view.backgroundColor = randomColor()
view.addSubview(colorButton)

PlaygroundPage.current.liveView = view

image of UIView in for loop

Answer 1

问题是您重复使用了 cell 变量，所以最后它只引用了您创建的最后一个视图。因此，您的按钮操作只会更新最后一个视图。

您需要一个包含所有视图的数组。然后在按钮处理程序中，遍历它们并给每个新的随机颜色。

import UIKit
import PlaygroundSupport

let view = UIView(frame: CGRect(x: 0, y: 0, width: 500, height: 600))
let colorButton = UIButton(frame: CGRect(x: 460, y: 560, width: 30, height: 30))
let numberOfCellsOnAxis = 6
let cellDimensions = view.frame.height / CGFloat(numberOfCellsOnAxis)
var cells = [UIView]()

func randomColor() -> UIColor {
    let red = CGFloat(arc4random_uniform(256))
    let green = CGFloat(arc4random_uniform(256))
    let blue = CGFloat(arc4random_uniform(256))

    return UIColor(red: red / 255, green: green / 255, blue: blue / 255, alpha: 1)
}

class TakeAction {
    var tapCount = 0

    @objc func makeStuffHappen() {
        cells.forEach { [=10=].backgroundColor = randomColor() }
        tapCount += 1
        print("gesture recognized, colors have changed \(tapCount) times!")
    }
}

let takeAction = TakeAction()
colorButton.addTarget(takeAction, action: #selector(takeAction.makeStuffHappen), for: .touchUpInside)

for xAxis in 0..<numberOfCellsOnAxis {
    for yAxis in 0..<numberOfCellsOnAxis {
        let cell = UIView(frame: CGRect(x: CGFloat(xAxis) * cellDimensions, y: CGFloat(yAxis) * cellDimensions, width: cellDimensions, height: cellDimensions))
        cell.backgroundColor = randomColor()
        view.addSubview(cell)
        cells.append(cell)    
    }
}

colorButton.backgroundColor = .magenta

view.backgroundColor = randomColor()
view.addSubview(colorButton)

PlaygroundPage.current.liveView = view

为什么单击按钮时这些框的颜色不会改变？ (Swift)

Why won't the colors to these boxes change when button is clicked? (Swift)

ios

swift

swift-playground