Question

I have made extension for UIButton class. Now if I use it everything works good. But I have another class that create for me array with UIButton objects and here I have some problem.

I have Helper class with method that return for me array with UIButton objects.

In ViewController.m in viewDidLoad callback I request for this array and also here in ViewController.m I import my UIButton+Extension.m

So, now I have extension for each UIButton object that I will use in ViewController.m

But if I use extension I have got error on method that call

[thumbButton.titleLabel setFont:[UIFont fontWithName:@"Helvetica" size:11.0]];

but if I don’t use extension this method invoke correct.

this is my UIButton+Extension.h file

#import <UIKit/UIKit.h>

@interface UIButton (extension_button)

- (void)centerButtonToView:(UIView *)view;
- (UIImage *)cropeImage:(UIImageView *)imageView;

@end

this is my UIButton+Extension.m file

#import "UIButton+Extension.h"

@implementation UIButton (extension_button)

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

- (void)centerButtonToView:(UIView *)view {
    CGRect rect = view.frame;
    CGRect rectSelf = self.frame;
    rectSelf.origin.x = (rect.size.width / 2.0f - rectSelf.size.width / 2.0f) + rect.origin.x;
    rectSelf.origin.y = (rect.size.height / 2.0f - rectSelf.size.height / 2.0f) + rect.origin.y;
    self.frame = rectSelf;
}

- (UIImage *)cropeImage:(UIImageView *)imageView {    
    CGRect rect;
    rect.origin.x = self.frame.origin.x - imageView.frame.origin.x;
    rect.origin.y = self.frame.origin.y - imageView.frame.origin.y;
    rect.size.width = self.frame.size.width;
    rect.size.height = self.frame.size.height;    
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();    
    CGRect drawRect = CGRectMake(-rect.origin.x,-rect.origin.y, imageView.image.size.width, imageView.image.size.height);
    CGContextClipToRect(context, CGRectMake(0, 0, rect.size.width, rect.size.height));
    [imageView.image drawInRect:drawRect];
    UIImage* subImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return subImage; 
}

@end

Helper.m (method that return array for me and here I have problem on setFont method)

+ (NSMutableArray *)createThumbnailsForCropSize {

    CGFloat width = 0.0f;
    CGFloat start_pos = 0.0f;

    if (IS_IPHONE) {
        width = 320.0f;
        start_pos = 62.0f;
    }
    else {
        width = 768.0f;
        start_pos = 286.0f;
    }

    NSMutableArray *arr = [[NSMutableArray alloc] init];
    NSArray *resolutionArray = [NSArray arrayWithObjects:@"30x40",@"33x48",@"35x40",@"35x45",@"36x47",@"37x47",
                                @"40x50",@"40x60",@"43x55",@"45x50",@"50x50",@"50x70", nil];
    NSInteger pos_x = start_pos;
    NSInteger page = 0;
    for (NSInteger idx = 0; idx < 12; idx++) {
        if (idx%3 == 0 && idx != 0) {
            page++;
            pos_x = start_pos + width * page;
        }
        UIButton *thumbButton = [[UIButton alloc] init];
        [thumbButton setTag:idx];
        [thumbButton setFrame:CGRectMake(pos_x, 13, 60, 60)];
        [thumbButton setTitle:[NSString stringWithFormat:[resolutionArray objectAtIndex:idx]] forState:UIControlStateNormal];
        [thumbButton.titleLabel setFont:[UIFont fontWithName:@"Helvetica" size:11.0]];
        [thumbButton setTitle:@"!00" forState:UIControlStateNormal];
        [thumbButton setBackgroundImage:[UIImage imageNamed:@"block_without_photo.png"] forState:UIControlStateNormal];
        [arr addObject:thumbButton];
        pos_x += 68;
    }
    return arr;
}

Answer 1

You need to remove initWithFrame: from your category. By including it, you are removing the normal implementation, and this will be preventing your buttons from being created properly, you will in fact be returning a UIControl.

Calling the super implementation in a category does not call UIButton‘s implementation, but the superclass of UIButton – UIControl. Categories are different to subclasses. (And you shouldn’t subclass UIButton either, as it is a class cluster).

If you do have specialist initialisation code in there, you will have to add it to a separate method and call it during your creation loop.