iOS 顺传

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;

}