iOS Programming: Problem extending UIButton class

Question

I'm trying to extend UIButton class to add few methods but I'm having some problem when I try to init my object.

-(id)init{

UIImage* image = [UIImage imageNamed:@"button_background.png"];    
CGRect frame=  CGRectMake(100.0, 70.0, 45.0 ,45.0);

self.frame = frame;

[self setTitle:@"title" forState:UIControlStateNormal];
[self setBackgroundImage:image forState:UIControlStateNormal];
[self setImage:image forState:UIControlStateNormal];

NSLog(@"type: %d",self.buttonType);
NSLog(@"x: %f\ny: %f\nwidth: %f\nheight: %f",frame.origin.x, frame.origin.y ,frame.size.width, frame.size.height);
NSLog(@"x: %f\ny: %f\nwidth: %f\nheight: %f",self.frame.origin.x, self.frame.origin.y ,self.frame.size.width, self.frame.size.height);

if(self != nil){
    //
}
return self;

}

It seams to work fine, there are no warning or error during execution. But in the console appears some inconsistency between values of frame and self.frame, and of course the button does not appear on screen.

type: 0
x: 100.000000
y: 70.000000
width: 45.000000
height: 45.000000

x: 0.000000
y: 0.000000
width: 0.000000
height: -1.998576

Please help me I'm getting out of my mind! :\

Bear in mind that UIButton is a class cluster. See these SO questions related to subclassing UIButton: [1](http://stackoverflow.com/questions/5045672/create-uibutton-subclass/5045778#5045778), [2](http://stackoverflow.com/questions/823524/when-using-drawrect-for-uibutton-subclass/1086939#1086939), [3](http://stackoverflow.com/questions/3679239/making-a-custom-button-using-a-uiview-or-overriding-uibutton/3679398#3679398). — albertamg, May 21 '11 at 14:09
Also, it would be safest to subclass `UIControl` instead of `UIButton`. The first is meant for subclassing, the the second... — gcamp, May 21 '11 at 17:44

idz · Accepted Answer · 2014-04-07T21:40:24.797

When you are subclassing in Objective-C you must (1) override the designated initializer (2) call the designated initializer of the super-class. You do neither.

You should be doing something like this:

/** 
 * \brief Convenience class method to replace button method of UIButton
 */
+(id)myButton
{
    MyButton* myButton = [[MyButton alloc] 
                              initWithFrame:CGMakeRect(100.0, 70.0, 45.0, 45.0)];
    return [myButton autorelaase];
}

-(id)initWithFrame:(CGRect)f
{
    if(self = [super initWithFrame:f])
    {
        UIImage* image = [UIImage imageNamed:@"button_background.png"];    

        [self setTitle:@"title" forState:UIControlStateNormal];
        [self setBackgroundImage:image forState:UIControlStateNormal];
        [self setImage:image forState:UIControlStateNormal];

        NSLog(@"type: %d",self.buttonType);
        NSLog(@"x: %f\ny: %f\nwidth: %f\nheight: %f", NSStringFromCGRect(frame));
        NSLog(@"x: %f\ny: %f\nwidth: %f\nheight: %f", NSStringFromCGRect(self.frame));
    }
    return self;
}

Hope this helps. Let me know if you need more info.

score 0 · Answer 2 · answered May 21 '11 at 13:48

In that moment when you log you don't added the button to any view. Anyway the code must be look something like this?

-(id)init{



if(self != nil){
    UIImage* image = [UIImage imageNamed:@"button_background.png"];    
CGRect frame=  CGRectMake(100.0, 70.0, 45.0 ,45.0);

self.frame = frame;

[self setTitle:@"title" forState:UIControlStateNormal];
[self setBackgroundImage:image forState:UIControlStateNormal];
[self setImage:image forState:UIControlStateNormal];

NSLog(@"type: %d",self.buttonType);
NSLog(@"x: %f\ny: %f\nwidth: %f\nheight: %f",frame.origin.x, frame.origin.y ,frame.size.width, frame.size.height);
NSLog(@"x: %f\ny: %f\nwidth: %f\nheight: %f",self.frame.origin.x, self.frame.origin.y ,self.frame.size.width, self.frame.size.height);
}
return self;

By the way don't you forget call the superclass init ?

I add the button to the current view in another piece of code. Putting the code in the "if( self != nil)" is only to write safer code. However the real problem was that I didn't call the [super initWithFrame:frame] Now it works! Thank you! — i3ravi, May 21 '11 at 14:14

score 0 · Answer 3 · edited May 23 '17 at 10:00

0

I just answered a very similar question here: How to create a very custom uibutton like UITableViewCellStyleSubtitle in iOS

Like some other folks have pointed out, UIButton is a class cluster, so you probably don't want to subclass it. But instead of subclassing UIControl, you might find it easier to create a category of UIButton.

edited May 23 '17 at 10:00

Community

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answered May 27 '11 at 21:23

Chamara Paul

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iOS Programming: Problem extending UIButton class

3 Answers3