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Is there any way to detect when the Backspace/Delete key is pressed in the iPhone keyboard on a UITextField that is empty? I want to know when Backspace is pressed only if the UITextField is empty.

Based on the suggestion from @Alex Reynolds in a comment, I've added the following code while creating my text field:

[[NSNotificationCenter defaultCenter] addObserver:self
          selector:@selector(handleTextFieldChanged:)
              name:UITextFieldTextDidChangeNotification
            object:searchTextField];

This notification is received (handleTextFieldChanged function is called), but still not when I press the Backspace key in an empty field. Any ideas?

There seems to be some confusion around this question. I want to receive a notification when the Backspace key is pressed. That's it. But the solution must also work when the UITextField is already empty.

Palua answered 30/12, 2009 at 1:21 Comment(2)

2011/11 solution for empty UITextField using runtime trickery: bjhomer.blogspot.com/2011/11/… – Dotterel 17/11, 2011 at 16:36

For those who are struggling with this in SwiftUI you can find a full example for a real use case here(#76685422) – Pelfrey 19/11, 2023 at 16:39

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This may be a long shot but it could work. Try setting the text field's text to a zero width space character \u200B. When backspace is pressed on a text field that appears empty, it will actually delete your space. Then you can just reinsert the space.

May not work if the user manages to move the caret to the left of the space.

Macula answered 30/12, 2009 at 23:10 Comment(8)

Nice. I agree that it's pretty hacky, but I was considering something like this as a last resort. Thanks for the suggestion. – Palua 30/12, 2009 at 23:11

@Andrew, this is the approach I decided to take. It took a bit of code, but it's certainly effective. Thanks for the help instead of trying to tell me that I'm doing something wrong. – Palua 2/1, 2010 at 3:20

This technique may work on iPhone > 3.1.3, but it's hacky and may break on future versions, etc. I think I found a cleaner, more stable solution for how to detect a delete keyboard key press on the iPhone/iOS. – Rentroll 9/7, 2011 at 22:24

Note that you should also remove the space character when the text field is not being edited. Otherwise your placeholder text won't be visible. – Norford 24/9, 2011 at 16:47

I can confirm that delete isn't detected if the user manages to move the cursor to the left of the space. If you can figure out how to fix that, then you should also subclass UITextField and implement canPerformAction:withSender: to return NO for select: and selectAll: actions when the text is equal to the string @"\u200B". – Rentroll 19/10, 2011 at 21:56

^I recall code for being able to detect the user's cursor location... you could search for that and then recall the becomeFirstResponder method if they move the cursor (so it moves back) – Cabbage 14/1, 2013 at 23:12

Problem is that this doesn't work for secure test fields. Any ideas how to handle that? – Robby 30/7, 2013 at 23:24

Sorry, but this idea is bad. It's incredible hacky and shouldn't be the accepted answer with 30 or so upvotes. I would subclass UITextField instead, like some of the other commenters have mentioned. – Papilloma 26/6, 2015 at 20:19

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Swift 4:

Subclass UITextField:

// MyTextField.swift
import UIKit

protocol MyTextFieldDelegate: AnyObject {
    func textFieldDidDelete()
}

class MyTextField: UITextField {

    weak var myDelegate: MyTextFieldDelegate?

    override func deleteBackward() {
        super.deleteBackward()
        myDelegate?.textFieldDidDelete()
    }

}

Implementation:

// ViewController.swift

import UIKit

class ViewController: UIViewController, MyTextFieldDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        // initialize textField
        let input = MyTextField(frame: CGRect(x: 50, y: 50, width: 150, height: 40))

        // set viewController as "myDelegate"
        input.myDelegate = self

        // add textField to view
        view.addSubview(input)

        // focus the text field
        input.becomeFirstResponder()
    }

    func textFieldDidDelete() {
        print("delete")
    }

}

Objective-C:

Subclass UITextField:

//Header
//MyTextField.h

//create delegate protocol
@protocol MyTextFieldDelegate <NSObject>
@optional
- (void)textFieldDidDelete;
@end

@interface MyTextField : UITextField<UIKeyInput>

//create "myDelegate"
@property (nonatomic, assign) id<MyTextFieldDelegate> myDelegate;
@end

//Implementation
#import "MyTextField.h"

@implementation MyTextField

- (void)deleteBackward {
    [super deleteBackward];

    if ([_myDelegate respondsToSelector:@selector(textFieldDidDelete)]){
        [_myDelegate textFieldDidDelete];
    }
}

@end

Now simply add MyTextFieldDelegate to your UIViewController and set your UITextFields myDelegate to self:

//View Controller Header
#import "MyTextField.h"

//add "MyTextFieldDelegate" to you view controller
@interface ViewController : UIViewController <MyTextFieldDelegate>
@end

//View Controller Implementation
- (void)viewDidLoad {
    //initialize your text field
    MyTextField *input = 
     [[MyTextField alloc] initWithFrame:CGRectMake(0, 0, 70, 30)];

    //set your view controller as "myDelegate"
    input.myDelegate = self;

    //add your text field to the view
    [self.view addSubview:input];
}

//MyTextField Delegate
- (void)textFieldDidDelete {
    NSLog(@"delete");
}

Macy answered 4/4, 2013 at 1:52 Comment(3)

What will happen to my existing delegate methods in ViewController class if I set my textfield's delegate to subclass of UITextField instead of UIViewController – Eclipse 15/8, 2014 at 16:3

deleteBackward() won't be called if you return false in textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool – Michaella 6/2, 2019 at 12:12

For the called method (textFieldDidDelete) is there a non-hacky way to do something only when the text view (in my case) was already empty? I am using it to delete a row in a table but only when tapping backspace in an empty text view. My hacky solution is adding a bool to check. So the first time the text view is empty it changes the bool. The next time it deletes. (without the bool it deletes any time the text view is empty) – Embroideress 2/1, 2020 at 14:13

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Update: See JacobCaraballo's answer for an example that overrides -[UITextField deleteBackward].

Check out UITextInput, specifically UIKeyInput has a deleteBackward delegate method that always gets called when the delete key is pressed. If you're doing something simple, then you might consider just subclassing UILabel and making it conform to the UIKeyInput protocol, as done by SimpleTextInput and this iPhone UIKeyInput Example. Note: UITextInput and its relatives (including UIKeyInput) are only available in iOS 3.2 and later.

Rentroll answered 9/7, 2011 at 22:14 Comment(0)