'[Bool]' 到 'nil' 总是返回 true - SwiftUI 中的问题

Question

我试图确保用户在点击确认答案之前只能选择一个答案，而不是几个，但我一直收到错误。我知道布尔值不可能为零，如果它是真或假，但我不知道如何绕过这一点。如有任何帮助，我们将不胜感激：(错误发生在第'allOptions！=行nil｝'

import SwiftUI
struct SecondView: View {

//Creating Variables for Revision Topics
@State private var setOptionOne = false
@State private var setOptionTwo = false
@State private var setOptionThree = false

@State private var questionIndex = 0
let button = ["Confirm Answer"]
@State public var buttonConfirm = [Int?]()
private var allOptions: [Bool] {
[setOptionOne, setOptionTwo, setOptionThree]}
private var oneOption: Bool {
allOptions.contains { $0 }}
private var isQuestionValid: Bool {
allOptions != nil}
var body: some View {

ScrollView{
VStack(spacing: 1.0) {

Group {
VStack {
Text(ResearchMCQ[questionIndex].question)
.padding(EdgeInsets(top: 10, leading: 10, bottom: 0, trailing: 10))
}

//Ensures Only One Answer Can Be Selected
let OptionOne = Binding<Bool>(get: { self.setOptionOne }, set: { self.setOptionOne = $0; self.setOptionTwo = false; self.setOptionThree = false })
let OptionTwo = Binding<Bool>(get: { self.setOptionTwo }, set: { self.setOptionOne = false; self.setOptionTwo = $0; self.setOptionThree = false })
let OptionThree = Binding<Bool>(get: { self.setOptionThree }, set: { self.setOptionOne = false; self.setOptionTwo = false; self.setOptionThree = $0 })
//Shows User MCQ Options
VStack {
Toggle(ResearchMCQ[questionIndex].options[0], isOn: OptionOne)
.toggleStyle(.button)
.tint(Color(red: 0.8, green: 0.8, blue: 0.8))
.foregroundColor(Color("Black-White"))
Toggle(ResearchMCQ[questionIndex].options[1], isOn: OptionTwo)
.toggleStyle(.button)
.tint(Color(red: 0.8, green: 0.8, blue: 0.8))
.foregroundColor(Color("Black-White"))
Toggle(ResearchMCQ[questionIndex].options[2], isOn: OptionThree)
.toggleStyle(.button)
.tint(Color(red: 0.8, green: 0.8, blue: 0.8))
.foregroundColor(Color("Black-White"))
}
}

HStack(spacing: 15) {
ForEach(0..<button.count, id: .self) {button in
Button {
// Make sure the index doesn't go beyond the array size
if ResearchMCQ.count > questionIndex + 1 {
questionIndex += 1
}
} label: {
Text("Confirm Answer")
}

.padding(.vertical, 12.5)
.padding(.horizontal, 120)
.foregroundColor(.white)
.foregroundStyle(.background)
.clipShape(Capsule())
.background(2 == button ? Color.primary: Color.secondary)
.clipShape(Capsule()).disabled(!isQuestionValid)
}
}
}

//Allows Header To Be Displayed
.navigationTitle("Research Methods Year 1 & 2")
.navigationBarBackButtonHidden(true)
.navigationBarTitleDisplayMode(.inline)

}
}

struct SecondView_Previews: PreviewProvider {
static var previews: some View {
SecondView()
}
}
}

Answer 1

allOptions不是可选的将其与nil进行比较，因此它始终是true比较，而您需要替换

allOptions != nil

带有

!allOptions.isEmpty

如果您需要检查true值的可用性，请执行

!allOptions.filter{ $0 }.isEmpty