FB10492871: TextField writes to binding twice

FB10492871.md

TextField writes to binding twice

FB10492871

The binding provided to a TextField is written to twice for each keystroke.

Run the following code in a SwiftUI application and type into the text field to reproduce:

import SwiftUI

struct ContentView: View {
  @State var text = ""
  var body: some View {
    TextField(
      "Type something here",
      text: .init(
        get: { self.text },
        set: {
          self.text = $0
          print("Binding set to \($0)")
        }
      )
    )
  }
}

If you apply a text field style other than .automatic it fixes the problem.

This can cause subtle bugs in applications that are hard to catch, such as if you want to track an analytics event anytime a text field is changed. You would knowningly double track all events.