显示键盘时，Form 中的 SwiftUI Picker 会立即弹回

Question

I have a Form in a NavigationView which displays an unknown number of fields for capturing customer input. Some fields are plain TextFields, others are Pickers with multiple selection. If the Picker is far enough down in the Form to be covered by the keyboard when a TextField is focused, then tapping the Picker with the keyboard up prevents the successful transition to the Picker's auto-generated detail view. The detail view is pushed and immediately popped, which prevents selection.

There are many other questions on this site relating to automatic popping of NavigationView/NavigationLinks, but I have replicated this issue in a simple single ContentView sample application and have identified a few key findings that lead me to believe this may be a bug:

1. The number of items in the Form prior to the Picker dictates whether this occurs, and differs based on screen size. For iPhone 13, 9+ TextFields before the Picker causes this to happen; for iPhone 13 Pro Max, 12+ TextFields before the Picker causes this to happen.
2. With the same number of total items in the Form, moving the Picker higher on the Form prevents this from happening. If the Picker will not be covered by the keyboard if any TextField is selected, the issue does not happen.
3. If the keyboard is not visible when tapping the Picker, the issue does not happen, regardless of the number of items in the Form.

class Model: ObservableObject {
    @Published var fields: [Field] = [
        Field(id: "1"), Field(id: "2"), Field(id: "3"), Field(id: "4"), Field(id: "5"), Field(id: "6"),
        Field(id: "7"), Field(id: "8"), Field(id: "9"), Field(id: "10"), Field(id: "11"), Field(id: "12"),
        Field(id: "13", type: .Picker(options: ["A", "B", "C"])),
    ]
}

struct Field: Identifiable {
    enum FieldType {
        case Text
        case Picker(options: [String])
    }
    
    let id: String
    let type: FieldType
    var value: String
    
    init(id: String, type: FieldType = .Text) {
        self.id = id
        self.type = type
        self.value = ""
    }
}

struct ContentView: View {
    
    @StateObject var model = Model()
    
    var body: some View {
        NavigationView {
            Form {
                Section {
                    ForEach($model.fields) { $field in
                        switch field.type {
                        case .Text:
                            TextField(field.id, text: $field.value)
                        case .Picker(let options):
                            Picker("Picker", selection: $field.value) {
                                ForEach(options, id: \.self) {
                                    Text($0)
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

Answer 1

I can confirm the issue. And I can add: also a programmatically activated NavigationLink pops back when hidden by the keyboard. I'd say its a bug.

Example based on OPs code, with additional programmatic Navlink:

struct ContentView: View {
    
    @StateObject var model = Model()
    @State private var selected = false
    
    var body: some View {
        NavigationView {
            Form {
                Section {
                    Button("activate hidden link") { selected = true }
                    ForEach($model.fields) { $field in
                        switch field.type {
                        case .Text:
                            TextField(field.id, text: $field.value)
                        case .Picker(let options):
                            Picker("Picker", selection: $field.value) {
                                ForEach(options, id: \.self) {
                                    Text($0)
                                }
                            }
                        }
                    }
                    NavigationLink("Test Link", isActive: $selected) {
                        Text("Destination")
                    }
                }
            }
        }
    }
}