How to convert a boolean expression to Binding<Bool> in SwiftUI?

Question

I have a textfield, and I am trying to goto another view when user input a specific string.

import SwiftUI

struct ContentView: View {
    @State var whether_go = "No"
    var body: some View {
                    TextField("Goto?", text: $whether_go)
                        .navigate(to: CircleImage(), when: whether_go == "Yes")
    }
}

This will raise error: Cannot convert value of type 'Bool' to expected argument type 'Binding<Bool>' Because when argument need a Binding<Bool>

I tried to use

when: Binding<Bool>(get: whether_happy == "Yes"))

This raise another error: No exact matches in call to initializer.

So what should I do to convert a boolean to Binding<Bool>?

David Pasztor · Accepted Answer · 2020-09-24 10:29:19Z

16

You need to use the Binding(get:set:) initialiser.

var body: some View {
        let binding = Binding<Bool>(get: { self.whether_go == "YES" }, set: { if $0 { self.whether_go = "YES"} else { self.whether_go = "NO" }})
        return TextField("Goto?", text: $whether_go)
                        .navigate(to: CircleImage(), when: binding)
    }

If you want the Binding to be 1-way, simply pass in an empty closure to set.

let binding = Binding<Bool>(get: { self.whether_go == "YES" }, set: { _ in })

Unrelated to your question, but why is whether_go a String and not a Bool? Also, you should follow Swift naming convention, which is lowerCamelCase for variable names (whetherGo).

answered Sep 24, 2020 at 10:29

David Pasztor

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1 Comment

Ninzero Over a year ago

Thanks for the answer. whether_go is not the original variable name, I changed this name to make is comprehensible.

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