Adding methods to a default class

Question

I'm looking to add a .owner and .number method to the UIButton class. I need to assign each individual number an (int)number so that I can use numbers to separate the buttons.

e.g so I could write buttonName.number = 1 and buttonName.owner = @"Player1";

How can I go about doing this?

Sandeep · Accepted Answer · 2012-11-24 00:56:28Z

2

There are few ways to do this thing. The easier one is to subclass the UIButton class and add the properties as you needed which could be achieved as;

@interface MyButton:UIButton
@property(nonatomic, assign) int number;
@property(nonatomic, strong) NSString *owner
@end

And the other way is to use runtime to add properties into the class. For this you would create a category for the class and then add property into the interface and then add properties to it using the runtime as;

@interface UIButton(MyCategory)
@property(nonatomic, assign) float number;
@property(nonatomic, strong) NSString *owner;
@end

@implementation UIButton(MYCategory)
NSString *const numberKey = @"kNumberKey";
NSString *const ownerKey = @"kOwnerKey";

 - (float)number{ 
    return [objc_getAssociatedObject(self, &numberKey) floatValue]; 
 } 

-(void)setNumber:(float)num{ 
  objc_setAssociatedObject(self, &numberKey,[NSNumber numberWithFloat:num], OBJC_ASSOCIATION_RETAIN_NONATOMIC); 
}

-(NSString*)owner{
    return objc_getAssociatedObject(self, &ownerKey);
}

-(void)setOwner:(NSString *)own{
    objc_setAssociatedObject(self, &ownerKey, own, OBJC_ASSOCIATION_COPY);
}

@end

With this you will be able to add the custom properties to the UIButton class itself.

edited Nov 24, 2012 at 0:56

answered Nov 23, 2012 at 23:04

Sandeep

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6 Comments

PappaSmalls Over a year ago

I made a category called UIButton and its a category of UIButton. I put the interface and implementation in there and get use of undeclared identifier 'number' and 'owner'

Sandeep Over a year ago

Make sure you have made correct imports for this. Use #import <objc/runtime.h>. Sorry I have missed something here. See my edits.

Sandeep Over a year ago

Well see it now. It should work. I was making some mistake myself instead of using the key and the value passed in methods, I was using something else.

Sandeep Over a year ago

Sorry, I was not checking the error in the code. But the edited code above is working implementation.

PappaSmalls Over a year ago

Thank you, it works but I'm having some problems with the number. Getting a conflicting return and parameter types for 'number' - 'int' vs 'NSNumber'. Compiles fine but when the button loads the program crashes.

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