===============Item==================
#import <Foundation/Foundation.h>
@interface Item : NSObject
@property (nonatomic,strong)NSString*name;
@property (nonatomic,assign)double price;
@end
#import "Item.h"
@implementation Item
@synthesize name,price;
@end
===============ItemView==================
#import <Foundation/Foundation.h>
@class Item;
@interface ItemView : NSObject
@property (nonatomic,strong) Item*item;
-(void)showItemInfo;
@end
#import "ItemView.h"
#import "Item.h"
@implementation ItemView
@synthesize item=_item;
-(void)showItemInfo{
NSLog(@"name=%@,price=%f",_item.name,_item.price);
}
-(void)setItem:(Item *)item{
self->_item = item;
//为item添加监器，监听item的name属性的改变
[self.item addObserver:self forKeyPath:@"name" options:NSKeyValueObservingOptionNew context:nil];
//为item添加监器，监听item的price属性的改变
[self.item addObserver:self forKeyPath:@"price" options:NSKeyValueObservingOptionNew context:nil];
}
//重写方法，当被监听的数据模型发生改变时，就会回调监听器的方法
-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
NSLog(@"===observeValueForKeyPath方法被调用===");
NSLog(@"被修改的keyPath为:%@",keyPath);
NSLog(@"被修改的对象为:%@",object);
NSLog(@"被修改的属性的值为:%@",[change objectForKey:@"new"]);
NSLog(@"被修改的上下午为:%@",context);
}
-(void)dealloc{
[self.item removeObserver:self forKeyPath:@"name"];
[self.item removeObserver:self forKeyPath:@"price"];
}
@end
===============main==================
#import <Foundation/Foundation.h>
#import "ItemView.h"
#import "Item.h"
int main(int argc, const char * argv[]) {
@autoreleasepool {
Item* item = [[Item alloc]init];//修改属性
//设置item属性
item.name = @"IOS";
item.price = 109;
ItemView * itemView = [[ItemView alloc]init];
[itemView setItem:item];
[itemView showItemInfo];
item.name = @"JAVA";
item.price = 888;
}
return 0;
}