How to detect keyboard events on hardware keyboard on iPhone (iOS)

Question

I have an app with a login page that has three fields for three different random characters. When the user leaves the last field, the soft keyboard disappears and the user can touch a "login" button on screen.

When there is a hardware keyboard (bluetooth or physical) attached, I'd like to be able to hit "enter" on it. However because the user is not in a field, I can't see how to detect this key being pressed.

Would anyone have advice on which class handles key press events? Presumably there is a delegate that I can use to receive these but my searches through the SDK haven't found anything.

Thanks

score 15 · Answer 1 · edited Feb 16 '21 at 07:46

15

For iOS 7.0 or later, you can return UIKeyCommands for the keyCommands property from any UIResponder, such as UIViewController:

Objective-C

// In a view or view controller subclass:
- (BOOL)canBecomeFirstResponder
{
    return YES;
}

- (NSArray *)keyCommands
{
    return @[ [UIKeyCommand keyCommandWithInput:@"\r" modifierFlags:0 action:@selector(enterPressed)] ];
}

- (void)enterPressed
{
    NSLog(@"Enter pressed");
}

Swift

// In a UIView/UIViewController subclass:
override var canBecomeFirstResponder: Bool {
    true
}

override var keyCommands: [UIKeyCommand]? {
    return [ UIKeyCommand(input: "\r", modifierFlags: [], action: #selector(enterPressed)) ]
}

@objc func enterPressed() {
    print("Enter pressed")
}

edited Feb 16 '21 at 07:46

mmackh

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answered Mar 03 '14 at 00:39

Patrick Pijnappel

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This will override any other text input fields. – Oliver Dixon Jul 10 '18 at 13:09
Do you know if it's possible to get the event type? keyUp keyDown? – calmar May 11 '20 at 15:50
1

see here: https://stackoverflow.com/a/61312598/7487013 – MrStahlfelge Jul 07 '20 at 15:00

score 1 · Answer 2 · answered Feb 05 '15 at 22:36

1

As a followup to the response by @Patrick, here is how you do it in Xamarin.iOS:

public override bool CanBecomeFirstResponder
{
    get { return true; }
}

public override UIKeyCommand[] KeyCommands
{
    get
    {
         return new[]{ UIKeyCommand.Create((NSString)"\r", (UIKeyModifierFlags)0, new ObjCRuntime.Selector("enterPressed")) };
    }
}

[Export("enterPressed")]
private void OnEnterPressed()
{
    // Handle Enter Key
}

answered Feb 05 '15 at 22:36

Kraig McConaghy

258
4
4

Keep in mind this will override any other text inputs on the app. – Oliver Dixon Jul 10 '18 at 13:12

score 1 · Accepted Answer · answered Sep 15 '10 at 16:07

1

One way to accomplish this is to have a hidden extra (4th in your case) text field. Make it 1x1 px in size and transparent. Then make it the first responder when any of your other 3 text fields are not, and look for text change events in that hidden field to trigger your key input event.

You might also want to check the notification for a software keyboard appearing if you don't want it to stay visible as well.

answered Sep 15 '10 at 16:07

hotpaw2

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Hey, do you have a code example of how that would work? Especially how I hide the keyboard for the hidden textfield. – Sebastian Wramba Oct 28 '10 at 10:34

How to detect keyboard events on hardware keyboard on iPhone (iOS)

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