iphone - 子类化 UIButton 添加一个属性

Question

我想将 UIButton 子类化以添加一些我需要的属性(不是方法...只有属性)。

这里是我的子类的代码:

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

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

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

@end

下面是我如何使用这个类:

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

我从哪里得到这个错误:

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

因此，从 ButtonWithType 我获得了一个 UIRoundedRectButton 并且 (Mybutton *) 无法施放它... 我需要做什么才能获得 MyButton 对象？ -init 是唯一的解决方案吗？

谢谢!

Answer 1

尝试使用 Associative References 的类别反而。它更简洁，适用于 UIButton 的所有实例。

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

//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);