简单的记录一下,其实很简单的问题，UI图片做的小点就OK,每个人都会遇到吧,那就把代码贴近来,自己写粘贴吧

import <UIKit/UIKit.h>

@interface UIButton (Extensions)

• (void)setEnlargeEdgeWithTop:(CGFloat) top right:(CGFloat) right bottom:(CGFloat) bottom left:(CGFloat) left;
  @end

import "UIButton+Extensions.h"

import <objc/runtime.h>

@implementation UIButton (Extensions)

static char topNameKey;
static char rightNameKey;
static char bottomNameKey;
static char leftNameKey;

• (void)setEnlargeEdge:(CGFloat) size
  {
  objc_setAssociatedObject(self, &topNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
  objc_setAssociatedObject(self, &rightNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
  objc_setAssociatedObject(self, &bottomNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
  objc_setAssociatedObject(self, &leftNameKey, [NSNumber numberWithFloat:size], OBJC_ASSOCIATION_COPY_NONATOMIC);
  }

• (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);
  }

• (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;
  }
  }
  //重写

• (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
  {
  CGRect rect = [self enlargedRect];
  if (CGRectEqualToRect(rect, self.bounds))
  {
  return [super pointInside:point withEvent:event];
  }
  return CGRectContainsPoint(rect, point) ? YES : NO;
  }

@end

直接调用
[UIButton setEnlargeEdgeWithTop:10 right:10 bottom:10 left:10];