子类 UIButton 添加属性 [英] Subclass UIButton to add a property

问题描述

我想继承 UIButton 以添加一些我需要的属性(不是方法...只有属性).

I'd like to subclass UIButton to add some properties that i need (not methods... only properties).

这里是我的子类的代码:

Here the code of my subclass:

//.h-----------------------
@interface MyButton : UIButton{
    MyPropertyType *property;
}

@property (nonatomic,retain) MyPropertyType *property;
@end

//.m--------------------------
@implementation MyButton
@synthesize property;

@end

这里是我如何使用这个类:

And here how I use the class:

MyButton *btn = ((MytButton *)[MyButton buttonWithType:UIButtonTypeRoundedRect]);
btn.property = SomeDataForTheProperty;

我从哪里得到这个错误:

From where i obtain this error :

 -[UIRoundedRectButton setProperty:]: unrecognized selector sent to instance 0x593e920

因此，从 ButtonWithType 我获得了一个 UIRoundedRectButton 并且 (Mybutton *) 不能转换它...我必须做什么才能获得 MyButton 对象?-init 是唯一的解决方案吗?

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 ?

谢谢！

推荐答案

尝试使用带有 关联引用.它更简洁，适用于 UIButton 的所有实例.

Try using a category with Associative References instead. It is much cleaner and will work on all instances of UIButton.

UIButton+Property.h

UIButton+Property.h

#import <Foundation/Foundation.h>

@interface UIButton(Property)

@property (nonatomic, retain) NSObject *property;

@end

UIButton+Property.m

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

//示例用法

#import "UIButton+Property.h"

...

UIButton *button1 = [UIButton buttonWithType:UIButtonTypeRoundedRect];
button1.property = @"HELLO";
NSLog(@"Property %@", button1.property);
button1.property = nil;
NSLog(@"Property %@", button1.property);

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