runtime添加关联对象

runtime给button添加block属性

1. runtime添加成员变量方法

/**
* object: 需要添加属性的类
* key: 唯一标示，可以是static修饰的变量的地址
* value: 需要添加的属性
* policy: 添加属性的类型（OBJC_ASSOCIATION_COPY_NONATOMIC等）
*/
objc_setAssociatedObject(<#id  _Nonnull object#>, <#const void * _Nonnull key#>, <#id  _Nullable value#>, <#objc_AssociationPolicy policy#>)

2、button分类代码如下：

static int AssociatedClosure = 0;

- (void)handleClickCallBack:(ButtonClickCallback)callBack {
    [self handleClickEvent:UIControlEventTouchUpInside callBack:callBack];
}


- (void)handleClickEvent:(UIControlEvents)aEvent
                callBack:(ButtonClickCallback)callBack {
    objc_setAssociatedObject(self, &AssociatedClosure, callBack, OBJC_ASSOCIATION_COPY_NONATOMIC);
    [self addTarget:self action:@selector(buttonClick) forControlEvents:aEvent];
}

- (void)buttonClick {
    ButtonClickCallback callBack = objc_getAssociatedObject(self, &AssociatedClosure);
    if (callBack != nil) {
        callBack(self);
    }
}

runtime扩大button点击范围

1. 使用到objc_setAssociatedObject和objc_getAssociatedObject添加top、bottom、left、right.

- (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 *leftEdge = objc_getAssociatedObject(self, &leftNameKey);
    NSNumber *bottomEdge = objc_getAssociatedObject(self, &bottomNameKey);
    
    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 + bottomEdge.floatValue);
    } else {
        return self.bounds;
    }
}

2. hitTest此方法返回的View是本次点击事件需要的最佳View

- (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;
}