当我尝试将 Toggle 的输出分配给旧变量时，它说: Binding<Bool>不可转换为 &lt;Bool&gt; [英] When I try and assign the output of the Toggle to an old variable it says: Binding&lt;Bool&gt; is not convertible to &lt;Bool&gt;

问题描述

当我尝试将 Toggle 的输出分配给旧变量时，它说:绑定不能转换为 bool.有没有办法来解决这个问题.我正在 Swift Playgrounds 中编写此代码.下面的代码是不起作用的部分

When I try and assign the output of the Toggle to an old variable it says: Binding is not convertible to bool. Is there a way to fix this. I am coding this in Swift Playgrounds. The code below is the part which doesn't function

import SwiftUI
import PlaygroundSupport

struct ContentView : View {

    @State private var redButton = false
    @State private var step = 0
    @State private var washingHandsToggle = true
    @State private var wearingMaskToggle = true
    @State private var coverMouthToggle = true
    @State private var quarantineToggle = true
    @State private var text = ""
    @State private var slide = 20.0
    @State private var slidetwo = 500000.0
    @State private var r0 = 0
    @State private var rvalues = [6.5, 6.1, 5.3, 4.8, 4.2, 3.5, 3.1, 2.9, 1.75, 1.5, 1.2, 1.0, 0.92, 0.82, 0.75, 0.7]

    var body: some View {
        VStack {
            VStack {
                Toggle(isOn: $washingHandsToggle) {
                    Text("Washing Hands Regularly")
                }.padding(.horizontal, 50)
                    .padding(.vertical, 25)

                Toggle(isOn: $wearingMaskToggle) {
                    Text("Wearing a Protective Mask")
                }.padding(.horizontal, 50)
                    .padding(.vertical, 25)

                Toggle(isOn: $coverMouthToggle) {
                    Text("Cover Mouth When Sneezing")
                }.padding(.horizontal, 50)
                    .padding(.vertical, 25)


                Toggle(isOn: $quarantineToggle) {
                    Text("Quarantine")
                }.padding(.horizontal, 50)
                    .padding(.vertical, 25)
                    .padding(.bottom, 30)
                r0 = rvalues[(wearingMaskToggle ? 1:0) + (washingHandsToggle ? 2:0) + (quarantineToggle ? 8:0) + (coverMouthToggle ? 4:0)]

                if !washingHandsToggle && !wearingMaskToggle && !quarantineToggle {
                    Text("Select At least 1")
                }else {
                    Text("Your R") + Text("0")
                        .font(.system(size: 15.0))
                        .baselineOffset(-6.0) + Text("Value Is")


                    Text("\(r0)")

                }

推荐答案

你不能只在 VStack 的中间设置 r0.通常，如果您开始在函数构建器中编写普通语句(例如赋值、循环、方法调用)，例如 VStack.init 的闭包参数，则会变得非常混乱.

You can't just set r0 in the middle of a VStack. In general, it becomes very messy if you start writing normal statements like assignment, loops, method calls, in a function builder, like the closure argument to VStack.init.

你最好让 r0 成为一个计算属性:

You'd better make r0 a computed property:

var r0 : Double {
    rvalues[(wearingMaskToggle ? 1:0) + (washingHandsToggle ? 2:0) + (quarantineToggle ? 8:0) + (coverMouthToggle ? 4:0)]
}

并删除您设置 r0 的行.

And delete the line where you set r0.

else 分支中的四个 Text 之一缺少 +.你应该写:

One of the four Texts in the else branch is missing a +. You should write:

Text("Your R") +
Text("0 ")
    .font(.system(size: 15.0))
    .baselineOffset(-6.0) +
Text("Value Is ") +
Text("\(r0)")

另外，我注意到您没有在 if 语句中包含 coverMouthToggle.这可能是一个错字...

Also, I noticed you did not include coverMouthToggle in the if statement. That might be a typo...

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