SwiftUI Picker doesn't select struct on MacOS

Question

I have a Picker inside a View:

       Form {
            Section {
                Picker("Style instance:", selection: $global.selectedStyle) {
                    ForEach(global.axes.instances.indices, id:\.self) { index in
                        return HStack {
                            let instance = global.axes.instances[index]
                            Text("\(instance.name)")//.tag(index)
                            Spacer()
                            Text(" \(instance.coordinates.description)")
                        }
                    }
                }
                .pickerStyle(PopUpButtonPickerStyle())
            }
        }

global is an defined as an @ObservedObject, inside:

@Published public var selectedStyle: StyleInstance? {
    didSet {
        print ("Changed \(selectedStyle?.description ?? "Nothing selected")")
        if let selected = selectedStyle {
            for index in axes.indices {
                axes[index].at =  Double(selected.coordinates[index])
            }
        }
    }
}

StyleInstance is simple struct:

public struct StyleInstance: Hashable, Codable {
    
    public static var emptyName = "<normal>" //this string will be replaced by empty string
    public let name: String
    public let coordinates: [Int]

    // init removes word `<normal>` and spaces
    init(name: String, coordinates:[CoordUnit]) {
        self.name = name.split(separator: " ").filter({$0 != StyleInstance.emptyName}).joined(separator: " ")
        self.coordinates = coordinates.map {Int($0)}
    }
}

When I change selection in Picker, selectedInstance .. {didSet.. is fired, but it's always nil

Wai Ha Lee · Accepted Answer · 2020-10-11 18:13:16Z

4

You need to apply a .tag modifier to the HStack inside the ForEach. Since your selection binding is to an Optional<StyleInstance>, you need to force the tag values to be optional also:

ForEach(global.axes.instances.indices, id:\.self) { index in
    return HStack {
        let instance = global.axes.instances[index]
        Text("\(instance.name)")//.tag(index)
        Spacer()
        Text(" \(instance.coordinates.description)")
    }.tag(global.axes.instances[index] as Optional)
}

edited Oct 11, 2020 at 18:13

Wai Ha Lee

8,856102 gold badges61 silver badges100 bronze badges

answered Oct 11, 2020 at 4:23

rob mayoff

387k69 gold badges842 silver badges887 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

SwiftUI Picker doesn't select struct on MacOS

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related