目的: 以block的形式给button添加点击事件
使用：
UIButton *btn=[UIButton buttonWithType:UIButtonTypeSystem];
[btn setTitle:title forState:UIControlStateNormal];
[btn addEventHandler:^(id sender) {
} forControlEvents:UIControlEventValueChanged];
实现：
.h
#import <UIKit/UIKit.h>
#import <objc/runtime.h>
typedef void (^ActionBlock)(id sender);
@interface UIControl (Blocks)
- (void)addEventHandler:(ActionBlock)handler forControlEvents:(UIControlEvents)controlEvents;
@end
.m
#import "UIControl+Blocks.h"
static char UIButtonHandlerKey;
@implementation UIControl (Blocks)
- (void)addEventHandler:(ActionBlock)handler forControlEvents:(UIControlEvents)controlEvents
{
objc_setAssociatedObject(self, &UIButtonHandlerKey, handler, OBJC_ASSOCIATION_COPY_NONATOMIC);
[self addTarget:self action:@selector(callActionHandler:) forControlEvents:controlEvents];
}
- (void)callActionHandler:(id)sender
{
ActionBlock handler = (ActionBlock)objc_getAssociatedObject(self, &UIButtonHandlerKey);
if (handler) {
handler(sender);
}
}
@end
