[iPhone] Why can't a UITextField be its own delegate?

WT Sat, 25 Jul 2009 12:08:34 -0700

Hello all,

I need to create a subclass of UITextField for a text field thatperforms some control over its own editing. The obvious idea is tomake the subclass instance set itself up as its own delegate, but thatfreezes the app as soon as the delegate method -textFieldDidBeginEditing returns.

Looking at Activity Monitor, the CPU usage of the app goes up tonearly 100%. I've since created the most trivial app with aUITextField subclass that conforms to the UITextFieldDelegate protocoland which sets itself up as its own delegate and, sure enough, the appfreezes.

Here's the subclass. Set up a project then add a text field to a viewand make its class be CustomTextField. Compile and run, and watch itfreeze when you attempt to edit the text in the field.


So... why can't the field be its own delegate?

Thanks in advance.
Wagner


// CustomTextField.h:

#import <UIKit/UIKit.h>

@interface CustomTextField: UITextField <UITextFieldDelegate>
{
}

@end

// CustomTextField.m:

#import "CustomTextField.h"

@implementation CustomTextField

- (void) awakeFromNib
{
    super.delegate = self;
    super.text = @"Hello world";

    NSLog(@"awakeFromNib called - delegate set to self");
}

//========================================================================= //


- (BOOL) textField: (UITextField*) text_field
         shouldChangeCharactersInRange: (NSRange) range
         replacementString: (NSString*) string
{

NSLog(@"-textField: shouldChangeCharactersInRange:replacementString:");

    return YES;
}

//========================================================================= //


- (BOOL) textFieldShouldBeginEditing: (UITextField*) text_field
{
    NSLog(@"-textFieldShouldBeginEditing:");
    return YES;
}

//========================================================================= //


- (void) textFieldDidBeginEditing: (UITextField*) text_field
{
    NSLog(@"-textFieldDidBeginEditing:");
}

//========================================================================= //


- (BOOL) textFieldShouldEndEditing: (UITextField*) text_field
{
    NSLog(@"-textFieldShouldEndEditing:");
    return YES;
}

//========================================================================= //


- (void) textFieldDidEndEditing: (UITextField*) text_field
{
    NSLog(@"-textFieldDidEndEditing:");
}

//========================================================================= //


- (BOOL) textFieldShouldClear: (UITextField*) text_field
{
    NSLog(@"-textFieldShouldClear:");
    return YES;
}

//========================================================================= //


- (BOOL) textFieldShouldReturn: (UITextField*) text_field
{
    NSLog(@"-textFieldShouldReturn:");
    [self resignFirstResponder];
    return YES;
}

//========================================================================= //


@end

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[iPhone] Why can't a UITextField be its own delegate?

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