* Get the existing observation information, creating it (and changing * the receiver to start key-value-observing YES) { /* * The instance is no longer being observed ... so we can * turn off key-value-observing
KVO (key-value-observing) 是一种 键值观察 机制, 它允许当前对象去观察目标对象的某个属性的变化; 当被观察对象的属性发生变化后, 会通过特定方法通知观察者对象属性变化的一些情况内容
content"]; [self.navigationController pushViewController:subVC animated:YES]; } 2.8 KVO传值 方法描述:KVO(Key-Value-Observing
示例: KVO(Key-Value-Observing)机制: 通知(notification)机制,NSNotificationCenter 代理模式 就像是java中的接口,类可以实现或不实现协议