当我尝试将Toggle的输出分配给旧变量时，它说：Binding 无法转换为

Question

[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中对此进行编码。以下代码是无效的部分

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)")

                }

Answer 1

您不能只将r0设置在VStack的中间。通常，如果您开始在函数构建器中编写诸如赋值，循环，方法调用之类的普通语句（例如VStack.init的闭包参数），则会变得非常混乱。

您最好将r0设为计算属性：

var r0 : Double {
    rvalues[(wearingMaskToggle ? 1:0) + (washingHandsToggle ? 2:0) + (quarantineToggle ? 8:0) + (coverMouthToggle ? 4:0)]
}
并删除设置r0的行。

Text分支中的四个else之一缺少+。您应该写：

Text("Your R") +
Text("0 ")
    .font(.system(size: 15.0))
    .baselineOffset(-6.0) +
Text("Value Is ") +
Text("\(r0)")
[此外，我注意到您在if语句中没有包含coverMouthToggle。这可能是一个错字...