Subclassing UITextField

Question

I'd like to create a text field which uses the number pad and accepts only numbers, even when pasted. Currently, I have a header as such:

#import <UIKit/UIKit.h>

@interface DRPNumberTextField : UITextField <UITextFieldDelegate>

@end

and an implementation:

#import "DRPNumberTextField.h"

@implementation DRPNumberTextField

- (id) initWithFrame:(CGRect)frame
{
  self = [super initWithFrame:frame];
  if (self)
  {
    self.delegate = self;
    [self setKeyboardType:UIKeyboardTypeNumberPad];
  }
  return self;
}

- (BOOL) textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
  if ([string rangeOfCharacterFromSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]].location != NSNotFound)
  {
    return NO;
  }
  return YES;
}

/*
 // Only override drawRect: if you perform custom drawing.
 // An empty implementation adversely affects performance during animation.
 - (void)drawRect:(CGRect)rect
 {
 // Drawing code
 }
 */

@end

I've set the text fields to use this class in the storyboard. However, my desired functionality does not occur. Moreover, as determined by debugging, initWithFrame: is never called. Any ideas? As more context, these text fields are embedded inside table cells of a table view of a table view controller. Of these, I provide a custom implementation of the table view controller here:

@interface DRPImplementSettingsViewController ()

@end

@implementation DRPImplementSettingsViewController

- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

@end

Thus it really has no implemented functionality beyond the stock. Its header is the obvious one.

EDIT: As some have pointed out, I don't need to subclass the text field to implement delegate functionality. I can put that elsewhere. But my question is this: why doesn't what I've presented here work? I can't find my mistake.

Answer 1

You need also override - (id)initWithCoder:(NSCoder *)decoder in your DRPNumberTextField. if you are using the custom UITextField in XIB or storyboard, initWithFrame: will not be called, initWithCoder: is called instead.