一行代码实现点击区域的扩大

UIView+ExtendTouchRect.m

void Swizzle(Class c, SEL orig, SEL new) {  
  Method origMethod = class_getInstanceMethod(c, orig);
  Method newMethod = class_getInstanceMethod(c, new);
  if (class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod))){
    class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
  } else {
    method_exchangeImplementations(origMethod, newMethod);
  }
}

@implementation UIView (ExtendTouchRect)

+ (void)load {
  Swizzle(self, @selector(pointInside:withEvent:), @selector(myPointInside:withEvent:));
}

- (BOOL)myPointInside:(CGPoint)point withEvent:(UIEvent *)event {
  if (UIEdgeInsetsEqualToEdgeInsets(self.touchExtendInset, UIEdgeInsetsZero) || self.hidden ||
      ([self isKindOfClass:UIControl.class] && !((UIControl *)self).enabled)) {
    return [self myPointInside:point withEvent:event]; // original implementation
  }
  CGRect hitFrame = UIEdgeInsetsInsetRect(self.bounds, self.touchExtendInset);
  hitFrame.size.width = MAX(hitFrame.size.width, 0); // don't allow negative sizes
  hitFrame.size.height = MAX(hitFrame.size.height, 0);
  return CGRectContainsPoint(hitFrame, point);
}

static char touchExtendInsetKey;  
- (void)setTouchExtendInset:(UIEdgeInsets)touchExtendInset {
  objc_setAssociatedObject(self, &touchExtendInsetKey, [NSValue valueWithUIEdgeInsets:touchExtendInset],
                           OBJC_ASSOCIATION_RETAIN);
}

- (UIEdgeInsets)touchExtendInset {
  return [objc_getAssociatedObject(self, &touchExtendInsetKey) UIEdgeInsetsValue];
}

@end