swift - 触摸手势识别器清除屏幕的随机功能

Question

我正在 Xcode 中构建一个拼贴画，其中包含一组背景图像和一个随机 int 函数来显示图像。

我尝试使用 tapGestureRecognizer 1)显示随机图像并 2)在使用 self.clearScreen 后清除屏幕。图像正在显示，但在显示下一个图像时它们不会消失。

import UIKit
import C4

class WorkSpace: CanvasController {

    override func setup() {


        var myRandomNumber: Int?

        //Background Image
        let background = Image("background")
        background?.constrainsProportions = true
        background?.width = self.canvas.width
        background?.height = self.canvas.height

        self.canvas.add(background)

        canvas.addTapGestureRecognizer { (locations, center, state) in
            self.clearScreen
            myRandomNumber = random(below: 4)
                }
            }

           if myRandomNumber == 1 {
            let tree = Image("Tree")
                tree?.constrainsProportions = true
                tree?.width = self.canvas.width
                tree?.origin = Point(0.0, self.canvas.height/2.0)
                self.canvas.add(tree)
                print("number1")
            }
            if myRandomNumber == 2 {
                let boy = Image("boy")
                boy?.constrainsProportions = true
                boy?.width = self.canvas.width
                boy?.origin = Point(0.0, self.canvas.height/2.0)
                self.canvas.add(boy)
            }
            if myRandomNumber == 3 {
                let woman = Image("woman")
                woman?.constrainsProportions = true
                woman?.width = self.canvas.width
                woman?.height = self.canvas.height
                self.canvas.add(woman)
           }
    }
}

我希望屏幕清除图片并替换为其他图片。

func clearScreen() { 
    for view in self.view.subView { 
        view.removeFromSuperView()
    }
} 

Answer 1

查看 C4 pods 后 docs :添加到 Canvas 后检查 View 层次结构

/// Adds a view to the end of the receiver’s list of subviews.
/// When working with C4, use this method to add views because it handles the addition of both UIView and View.
public func add<T>(_ subview: T?) {...}

然后尝试使用其提供的方法删除 subview :

/// Unlinks the view from the receiver and its window, and removes it from the responder chain.
/// Calling this method removes any constraints that refer to the view you are removing, or that refer to any view in the
/// subtree of the view you are removing.
/// When working with C4, use this method to add views because it handles the removal of both UIView and View.
/// ````
/// let v = View(frame: Rect(0,0,100,100))
/// let subv = View(frame: Rect(25,25,50,50))
/// v.add(subv)
/// v.remove(subv)
/// ````
/// - parameter subview:    The view to be removed.
public func remove<T>(_ subview: T?) {
    if let v = subview as? UIView {
        v.removeFromSuperview()
    } else if let v = subview as? View {
        v.view.removeFromSuperview()
    } else {
        fatalError("Can't remove subview of class `\(type(of: subview))`")
    }
}