点击区域扩大

之前有个需求，按钮很小会很难点到，于是就需要扩大点击区域，一个UIButton的分类和runtime能很好解决问题。

主要方法：

//各个方向扩大到相同大小，通过objc_setAssociatedObject关联到对象
- (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);

}

//可指定方向扩大，通过objc_setAssociatedObject关联到对象

- (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);

}

//然后就是扩大区域了

- (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

    {

        returnself.bounds;

    }

}

最后依然要考虑响应链的问题：

//点击的是这个区域，就响应button的事件

- (UIView*) hitTest:(CGPoint) point withEvent:(UIEvent*) event

{

    CGRectrect = [selfenlargedRect];

    if (CGRectEqualToRect(rect, self.bounds))

    {

        return[superhitTest:pointwithEvent:event];

    }

    returnCGRectContainsPoint(rect, point) ?self:nil;

}