FB13705289

Crash when projecting Binding to an unwrapped value

Basic Information

Which platform is most relevant for your report?

iOS

Which technology does your report involve?

SwiftUI

What type of feedback are you reporting?

Incorrect/Unexpected Behavior

What build does the issue occur on?

iOS 17.4 Seed 3 (21E5200d)

Where does the issue occur?

On device

Description

• Run the given code.
• Try out the picker to change the selection.
• Press "Remove selection" to cause the crash.
• I wouldn't expect this code to crash.

Evidence

Visual

Demo	Workaround

Code

AppleFeedback/FB13705289/demo.swift

Lines 1 to 37 in de5d7b8

	import SwiftUI
	struct ContentView: View {
	@State private var selection: Int?
	var body: some View {
	VStack {
	Picker("Picker", selection: $selection) {
	ForEach(0 ..< 3) { index in
	Text("Index \(index)")
	.tag(index as Int?)
	}
	}
	.pickerStyle(.segmented)
	Button("Remove selection") {
	selection = nil
	}
	if let $selection = Binding($selection) {
	OtherView(selection: $selection)
	}
	}
	}
	}
	struct OtherView: View {
	@Binding var selection: Int
	var body: some View {
	Text("Selection = \(selection)")
	}
	}
	#Preview {
	ContentView()
	}

AppleFeedback/FB13705289/workaround.swift

Lines 1 to 47 in de5d7b8

	import SwiftUI
	struct ContentView: View {
	@State private var selection: Int?
	var body: some View {
	VStack {
	Picker("Picker", selection: $selection) {
	ForEach(0 ..< 3) { index in
	Text("Index \(index)")
	.tag(index as Int?)
	}
	}
	.pickerStyle(.segmented)
	Button("Remove selection") {
	selection = nil
	}
	if let $selection = selectionBinding() {
	OtherView(selection: $selection)
	}
	}
	}
	private func selectionBinding() -> Binding<Int>? {
	guard selection != nil else {
	return nil
	}
	return Binding(
	get: { selection! },
	set: { selection = $0 }
	)
	}
	}
	struct OtherView: View {
	@Binding var selection: Int
	var body: some View {
	Text("Selection = \(selection)")
	}
	}
	#Preview {
	ContentView()
	}