@Binding and ForEach in SwiftUI

Question

I can't undertand how to use @Binding in combination with ForEach in SwiftUI. Let's say I want to create a list of Toggles from an array of booleans.

struct ContentView: View {     @State private var boolArr = [false, false, true, true, false]      var body: some View {         List {             ForEach(boolArr, id: \.self) { boolVal in                 Toggle(isOn: $boolVal) {                     Text("Is \(boolVal ? "On":"Off")")                 }                             }         }     } } 

I don't know how to pass a binding to the bools inside the array to each Toggle. The code here above gives this error:

Use of unresolved identifier '$boolVal'

And ok, this is fine to me (of course). I tried:

struct ContentView: View {     @State private var boolArr = [false, false, true, true, false]      var body: some View {         List {             ForEach($boolArr, id: \.self) { boolVal in                 Toggle(isOn: boolVal) {                     Text("Is \(boolVal ? "On":"Off")")                 }                             }         }     } }  

This time the error is:

Referencing initializer 'init(_:id:content:)' on 'ForEach' requires that 'Binding' conform to 'Hashable'

Is there a way to solve this issue?

Answer 1

You can use something like the code below. Note that you will get a deprecated warning, but to address that, check this other answer: https://stackoverflow.com/a/57333200/7786555

import SwiftUI  struct ContentView: View {     @State private var boolArr = [false, false, true, true, false]      var body: some View {         List {             ForEach(boolArr.indices) { idx in                 Toggle(isOn: self.$boolArr[idx]) {                     Text("boolVar = \(self.boolArr[idx] ? "ON":"OFF")")                 }             }         }     } } 

Answer 2

⛔️ Don't use a Bad practice!

Most of the answers (including the @kontiki accepted answer) method cause the engine to rerender the entire UI on each change and Apple mentioned this as a bad practice at wwdc2021 (around time 7:40)

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✅ Swift 5.5

From this version of swift, you can use binding array elements directly by passing in the bindable item like:

_{⚠️ Note that Swift 5.5 is not supported on iOS 14 and below but at least check for the os version and don't continue the bad practice!}