Is it possible to get textfield assosiated with a keyboard? - ios

Question

In my view controller I'm subscribed to UIKeyboardWillShowNotification:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:nil];
so in my keyboardWillShow: method I'm able to retrieve some info about the keyboard from the notification. But what I want is to get the reference to the actual text field which brings the keyboard up. I couldn't find how to do that in google and I suspect it might be impossible, but someone might know. If it is indeed impossible then I would like to know if there's a possibility to make it reverse way - to get the info about the keyboard by having the reference to the text field. Thanks

Answer 1

Let me emphasize that #iphonic comment is the right way to go.
You should use UITextField delegate function textFieldShouldBeginEditing:
Anything short of that is a kludge: UIKeyboardWillShowNotification assumes the software keyboard will show up, with is a very dangerous assumption and is likely to fail in all sorts of situations, starting with but not limited to Bluetooth keyboards. Try cmd-K in Simulator.
Here is aforementioned kludge, inspired by Get the current first responder without using a private API
func keyboardWillShow() {
let firstResponder = self.findFirstResponder(inView: self.view)
println("keyboardWillShow for \(firstResponder)")
}
func findFirstResponder(inView view: UIView) -> UIView? {
for subView in view.subviews as! [UIView] {
if subView.isFirstResponder() {
return subView
}
if let recursiveSubView = self.findFirstResponder(inView: subView) {
return recursiveSubView
}
}
return nil
}

Answer 2

There is one manual way
if ([firstName isFirstResponder]) {
// caused due to firstName
} else if ([lastName isFirstResponder]) {
// caused due to lastName
}
Swift
if firstName.isFirstResponder { // caused due to firstName }
else
if lastName.isFirstResponder { // caused due to lastName }

Answer 3

The easiest (and almost only) way to do this happens to also be the best way (as #iphonic mentioned)
Implement the UITextFieldDelegate delegate method textFieldShouldBeginEditing:textField
This method will be called before any other event (including any keyboard notifications)
Store the UITextField that received this delegate call to be referenced when determining which field triggered this event.
What I also recommend doing is, if you are looking to determine which keyboard fired the current keyboard appearance, within this delegate method simply register for receiving keyboard notifications.
- (BOOL)textFieldShouldBeginEditing:(UITextView *)textView {
[NSNotificationCenter.defaultCenter addObserver:self selector:#selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
return YES;
}
This way, you can be certain that when keyboardWillShow: is called, it was in fact triggered from this specific text field.
Of course, to make sure you keep track of your text fields correctly, stop listening when the text field stops editing.
- (void)textFieldDidEndEditing:(UITextView *)textView {
[NSNotificationCenter.defaultCenter removeObserver:self name:UIKeyboardWillShowNotification object:nil];
}

Answer 4

There is much better way to do this via did begin editing notifications of UITextField and UITextView:
UITextFieldTextDidBeginEditingNotification
and
UITextViewTextDidBeginEditingNotification
- (void)startListeningForKeyboardNotification {
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(responderDidBeginEditing:) name:UITextFieldTextDidBeginEditingNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(responderDidBeginEditing:) name:UITextViewTextDidBeginEditingNotification object:nil];
}
- (void)responderDidBeginEditing:(NSNotification *)notification {
if ([notification.object isKindOfClass:[UITextField class]]) {
UITextField *textField = notification.object;
// Do something with text field
} else if ([notification.object isKindOfClass:[UITextView class]]) {
UITextView *textView = notification.object;
// Do something with text view
}
}