Add lefthand margin to UITextField

As I have explained in a previous comment, the best solution in this case is to extend the UITextField class instead of using a category, so you can use it explicitly on the desired text fields.

#import <UIKit/UIKit.h>

@interface MYTextField : UITextField

@end


@implementation MYTextField

- (CGRect)textRectForBounds:(CGRect)bounds {
    int margin = 10;
    CGRect inset = CGRectMake(bounds.origin.x + margin, bounds.origin.y, bounds.size.width - margin, bounds.size.height);
    return inset;
}

- (CGRect)editingRectForBounds:(CGRect)bounds {
    int margin = 10;
    CGRect inset = CGRectMake(bounds.origin.x + margin, bounds.origin.y, bounds.size.width - margin, bounds.size.height);
    return inset;
}

@end

A category is intended to add new functions to an existing class, not to override an existing method.

You can do it by extending UITextField class and overriding two methods:

- (CGRect)textRectForBounds:(CGRect)bounds;
- (CGRect)editingRectForBounds:(CGRect)bounds;

Here is the code:

The interface in MYTextField.h

@interface MYTextField : UITextField

@end

Its implementation in MYTextField.m

@implementation MYTextField

static CGFloat leftMargin = 28;

 - (CGRect)textRectForBounds:(CGRect)bounds
{
    bounds.origin.x += leftMargin;

    return bounds;
}

 - (CGRect)editingRectForBounds:(CGRect)bounds
{
    bounds.origin.x += leftMargin;

    return bounds;
}
@end