1.在界面中难免会遇到UIImageView 太小了，不好点击所以要扩大它的点击范围。
我使用分类UIView+WJEnlargeArea实现：

Paste_Image.png

这样可以将greenView的点击范围加大40.

import "UIView+WJEnlargeArea.h"

import <objc/runtime.h>

@implementation UIView (WJEnlargeArea)
static const char topNameKey;
static const char rightNameKey;
static const char bottomNameKey;
static const char leftNameKey;

• (void) setEnlargeEdge:(CGFloat) edge
  {
  [self setEnlargeEdgeWithTop:edge right:edge bottom:edge
  left:edge];
  }
• (void) setEnlargeEdgeWithTop:(CGFloat) top right:(CGFloat) right bottom:(CGFloat) bottom left:(CGFloat) left
  {
  objc_setAssociatedObject(self, &topNameKey, [NSNumber numberWithFloat:top], OBJC_ASSOCIATION_COPY_NONATOMIC);
  NSNumber* topEdge = objc_getAssociatedObject(self, &topNameKey);
  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;
  }
  }
  -(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
  {
  CGRect rect = [self enlargedRect];
  return CGRectContainsPoint(rect, point)?self:nil;
  }
  @end