我們可以為UIButton建立一個Category，然后利用runtime的綁定屬性，來擴大響應區(qū)域。
先看一下.h文件里的仓蛆，只聲明了一個函數(shù)。使用的時候直接利用這個函數(shù)擴大四周的響應區(qū)域挎春。

#import <UIKit/UIKit.h>  
  
@interface UIButton (EnlargeTouchAera)  
- (void)setEnlargeEdgeWithTop:(CGFloat) top right:(CGFloat) right bottom:(CGFloat) bottom left:(CGFloat) left;  
@end  

下面是.m文件的實現(xiàn)部分看疙，首先定義四個靜態(tài)變量，是用來存儲上下左右的標志直奋。
然后重寫hitTest函數(shù)能庆，里面使用了我們自定義的enlargedRect方法。

#import "UIButton+EnlargeTouchAera.h"  
#import <objc/runtime.h>  
  
static char topNameKey;  
static char rightNameKey;  
static char bottomNameKey;  
static char leftNameKey;  
  
@implementation UIButton (EnlargeTouchAera)  
- (void)setEnlargeEdgeWithTop:(CGFloat)top right:(CGFloat)right bottom:(CGFloat)bottom left:(CGFloat)left {  
    objc_setAssociatedObject(self, &topNameKey, [NSNumber numberWithFloat:top], OBJC_ASSOCIATION_COPY_NONATOMIC);  
    objc_setAssociatedObject(self, &rightNameKey, [NSNumber numberWithFloat:right], OBJC_ASSOCIATION_COPY_NONATOMIC);  
    objc_setAssociatedObject(self, &bottomNameKey, [NSNumber numberWithFloat:bottom], OBJC_ASSOCIATION_COPY_NONATOMIC);  
    objc_setAssociatedObject(self, &leftNameKey, [NSNumber numberWithFloat:left], OBJC_ASSOCIATION_COPY_NONATOMIC);  
}  
  
- (UIView *)hitTest:(CGPoint) point withEvent:(UIEvent*) event {  
    CGRect rect = [self enlargedRect];  
    if (CGRectEqualToRect(rect, self.bounds)) {  
        return [super hitTest:point withEvent:event];  
    }  
    return CGRectContainsPoint(rect, point) ? self : nil;  
}  
  
- (CGRect)enlargedRect {  
    NSNumber * topEdge = objc_getAssociatedObject(self, &topNameKey);  
    NSNumber * rightEdge = objc_getAssociatedObject(self, &rightNameKey);  
    NSNumber * bottomEdge = objc_getAssociatedObject(self, &bottomNameKey);  
    NSNumber * leftEdge = objc_getAssociatedObject(self, &leftNameKey);  
    if (topEdge && rightEdge && bottomEdge && leftEdge) {  
        return CGRectMake(self.bounds.origin.x - leftEdge.floatValue,  
                          self.bounds.origin.y - topEdge.floatValue,  
                          self.bounds.size.width + leftEdge.floatValue + rightEdge.floatValue,  
                          self.bounds.size.height + topEdge.floatValue + bottomEdge.floatValue);  
    } else {  
        return self.bounds;  
    }  
}  
  
@end