ios 顺传一层的话，直接用属性 改变里面的值
顺传穿两到三层的话 使用KVO
// 设置item
- (void)setItem:(UITabBarItem *)item
{
_item = item;
// KVO 监听属性改变
[item addObserver:self forKeyPath:@"badgeValue" options:0 context:nil];
[item addObserver:self forKeyPath:@"title" options:0 context:nil];
[item addObserver:self forKeyPath:@"image" options:0 context:nil];
[item addObserver:self forKeyPath:@"selectedImage" options:0 context:nil];
[self observeValueForKeyPath:nil ofObject:nil change:nil context:nil];
}
- (void)dealloc
{
[self.item removeObserver:self forKeyPath:@"badgeValue"];
[self.item removeObserver:self forKeyPath:@"title"];
[self.item removeObserver:self forKeyPath:@"image"];
[self.item removeObserver:self forKeyPath:@"selectedImage"];
}
/**
* 监听到某个对象的属性改变了,就会调用
*
* @param keyPath 属性名
* @param object 哪个对象的属性被改变
* @param change 属性发生的改变
*/
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
// 设置文字
[self setTitle:self.item.title forState:UIControlStateSelected];
[self setTitle:self.item.title forState:UIControlStateNormal];
// 设置图片
[self setImage:self.item.image forState:UIControlStateNormal];
[self setImage:self.item.selectedImage forState:UIControlStateSelected];
// 设置提醒数字
self.badgeButton.badgeValue = self.item.badgeValue;
// 设置提醒数字的位置
CGFloat badgeY = 5;
CGFloat badgeX = self.frame.size.width - self.badgeButton.frame.size.width - 10;
CGRect badgeF = self.badgeButton.frame;
badgeF.origin.x = badgeX;
badgeF.origin.y = badgeY;
self.badgeButton.frame = badgeF;
}