Subclass UIButton to add a property - iphone

Question

I'd like to subclass UIButton to add some properties that i need (not methods... only properties).
Here the code of my subclass:
//.h-----------------------
#interface MyButton : UIButton{
MyPropertyType *property;
}
#property (nonatomic,retain) MyPropertyType *property;
#end
//.m--------------------------
#implementation MyButton
#synthesize property;
#end
And here how I use the class:
MyButton *btn = ((MytButton *)[MyButton buttonWithType:UIButtonTypeRoundedRect]);
btn.property = SomeDataForTheProperty;
From where i obtain this error :
-[UIRoundedRectButton setProperty:]: unrecognized selector sent to instance 0x593e920
Thus, from ButtonWithType i obtain a UIRoundedRectButton and (Mybutton *) can't cast it...
What i have to do to obtain a MyButton object ? is -init the unique solution ?
Thank you!

Answer 1

Try using a category with Associative References instead. It is much cleaner and will work on all instances of UIButton.
UIButton+Property.h
#import <Foundation/Foundation.h>
#interface UIButton(Property)
#property (nonatomic, retain) NSObject *property;
#end
UIButton+Property.m
#import "UIButton+Property.h"
#import <objc/runtime.h>
#implementation UIButton(Property)
static char UIB_PROPERTY_KEY;
#dynamic property;
-(void)setProperty:(NSObject *)property
{
objc_setAssociatedObject(self, &UIB_PROPERTY_KEY, property, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
-(NSObject*)property
{
return (NSObject*)objc_getAssociatedObject(self, &UIB_PROPERTY_KEY);
}
#end
//Example usage
#import "UIButton+Property.h"
...
UIButton *button1 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
button1.property = #"HELLO";
NSLog(#"Property %#", button1.property);
button1.property = nil;
NSLog(#"Property %#", button1.property);

Answer 2

You need to do:
MyButton *btn = [[MyButton alloc] init];
To create your button. The buttonWithType:UIButtonTypeRoundedRect only creates UIButton objects.
=== edit ===
If you wish to use a RoundedRect button; then I would suggest the following. Basically, we just create a UIView with whatever properties we want and add the desired button to that view.
.h
#interface MyButton : UIView
{
int property;
}
#property int property;
#end
.m
#implementation MyButton
#synthesize property;
- (id)initWithFrame:(CGRect)_frame
{
self = [super initWithFrame:_frame];
if (self)
{
UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
btn.frame = self.bounds;
[self addSubview:btn];
}
return self;
}
#end
Usage:
MyButton *btn = [[MyButton alloc] initWithFrame:CGRectMake(0, 0, 200, 20)];
btn.property = 42;
[self.view addSubview:btn];

Answer 3

I have a simple scheme that only involves a few library methods, no boilerplate, and just 3 lines of code for each property you want to add. There are two example properties added below: startPoint and tileState. For illustrative purposes here are the lines you'd need to add for a property like tileState:
//#property (assign, nonatomic) SCZTileState tileState; // tileState line 1
//#property (assign, nonatomic) SCZTileState tileState; // tileState line 2
//#dynamic tileState; // tileState line 3
There's more details in my blog post describing how this works
UIButton+SCZButton.h
#import <UIKit/UIKit.h>
#interface UIButton (SCZButton)
#property (readwrite, nonatomic) id assocData;
#end
UIButton+SCZButton.m
// UIButton+SCZButton.m
// Copyright (c) 2013 Ooghamist LLC. All rights reserved.
#import "UIButton+SCZButton.h"
#import <objc/runtime.h>
#implementation UIButton (SCZButton)
- (id)assocData {
id data = objc_getAssociatedObject(self, "SCZButtonData");
return data;
}
- (void)setAssocData:(id)data {
objc_setAssociatedObject(self, "SCZButtonData", data,
OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
#end
OOGTotallyTile.h
// UIButton+OOGTotallyTile.m
// Copyright (c) 2013 Ooghamist LLC. All rights reserved.
#import <UIKit/UIKit.h>
#import "UIButton+SCZButton.h"
#define kPointLabelTag 837459
typedef enum {
SCZTileStatePlaced,
SCZTileStateDropping,
SCZTileStateDropped
} SCZTileState;
#interface SCZButtonData : NSObject
#property (assign, nonatomic) CGPoint startPoint;
#property (assign, nonatomic) SCZTileState tileState; // tileState line 1
#end
#interface UIButton (OOGTotallyTile)
#property (readonly, nonatomic) SCZButtonData *buttonData;
#property (assign, nonatomic) CGPoint startPoint;
#property (assign, nonatomic) SCZTileState tileState; // tileState line 2
#end
OOGTotallyTile.m
// UIButton+OOGTotallyTile.m
// Copyright (c) 2013 Ooghamist LLC. All rights reserved.
#import "OOGTotallyTile.h"
#implementation SCZButtonData
#end
#implementation UIButton (OOGTotallyTile)
#dynamic startPoint;
#dynamic tileState; // tileState line 3
- (SCZButtonData*)buttonData {
if ( ! self.assocData) {
self.assocData = [[SCZButtonData alloc] init];
}
return self.assocData;
}
- (id)forwardingTargetForSelector:(SEL)aSelector {
id forwardingTarget = [super forwardingTargetForSelector:aSelector];
if ( ! forwardingTarget) {
return [self buttonData];
}
return forwardingTarget;
}
#end