Swiftui Form View jump up bug

问题

I had a problem when following Raywenderlich Tutorial. The form view will automatically jump upward a little bit every time i clicked an item. Is this a bug? Is there anyway to solve it? The code is below. And in Contentview, i used a GroupedListStyle() to list all the items. My xcode version is 11.2, Swift 5.

Below is TaskEditingView.swift

import SwiftUI

struct TaskEditingView: View {
    @Binding var task: Task

    var body: some View {
        Form {
            TextField("Name", text:$task.name)
            Toggle("Completed", isOn: $task.completed)
        }
    }
}

struct TaskEditingView_Previews: PreviewProvider {
    static var previews: some View {
        TaskEditingView(task: .constant(Task(name: "TO DO")))
    }
}

Below is ContentView.swift

import SwiftUI

struct ContentView: View {
    @ObservedObject var taskStore: TaskStore
    @State var modalIsPresented = false

    var body: some View {
        NavigationView {
            List {
                ForEach(taskStore.tasks) { index in
                    RowView(task: self.$taskStore.tasks[index])
                }
                .onMove { sourceIndices, destinationIndex in
                    self.taskStore.tasks.move(
                        fromOffsets: sourceIndices,
                        toOffset: destinationIndex
                    )
                }
                .onDelete { indexSet in
                    self.taskStore.tasks.remove(atOffsets: indexSet)
                }
            }
            .navigationBarTitle("Tasks")
            .navigationBarItems(
                leading: EditButton(),
                trailing:
                Button(
                    action: { self.modalIsPresented = true }
                ) {
                    Image(systemName: "plus")
                }
            )
        }
        .sheet(isPresented: $modalIsPresented) {
            NewTaskView(taskStore: self.taskStore)
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView( taskStore: TaskStore() )
    }
}

Below is RowView.swift

import SwiftUI

struct RowView: View {
    @Binding var task: Task

    let checkmark = Image(systemName: "checkmark")

    var body: some View {
        NavigationLink(
            destination: TaskEditingView(task: $task)
        ) {
            if task.completed {
                checkmark
            } else {
                checkmark.hidden()
            }

            Text(task.name)
                .strikethrough(task.completed)
        }
    }
}

struct RowView_Previews: PreviewProvider {
  static var previews: some View {
    RowView(
      task: .constant( Task(name: "To Do") )
    )
  }
}

ContentView.swift -> RowView.swift -> TaskEditingView.swift

回答1:

If you use a Section Inside of a form, the jumping bug is gone. If you use empty header and footer of a section, it should be look like you do it.

Form{
       Section(header: Text(""), footer: Text(""), content: {
           Text(...)
           Toggle(...)
       })
    }

回答2:

Workaround

By my findings it looks like Form layout issue, thus as a temporary solution the following workaround someone might find applicable:

Form {
    TextField("Name", text:$task.name)
    Toggle("Completed", isOn: $task.completed)
}
.navigationBarTitle("", displayMode: .inline) // !!!

来源：https://stackoverflow.com/questions/59242504/swiftui-form-view-jump-up-bug

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