iOS 监听回调机制KVO实例
监听某个对象，如果这个对象的数据发生变化，会发送给监听者从而触发回调函数
[self.beanaddObserver:selfforKeyPath:@"data"options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOldcontext:NULL];
这个就是注册监听，这个@“data”作为标识符方便回调函数辨认
-(void)observeValueForKeyPath:(NSString*)keyPathofObject:(id)objectchange:(NSDictionary*)changecontext:(void*)context
{
if([keyPathisEqualToString:@"data"])
{
self.label.text=[self.beanvalueForKey:@"data"];
}
}
这个就是回调函数，分辨是哪个对象发生变化，然后给与相应的处理
-(void)viewWillDisappear:(BOOL)animated{
[self.beanremoveObserver:selfforKeyPath:@"data"];
}
既然有注册监听还记得解除监听
以下是完整例子代码
//
//ViewController.m
//First
//
//Createdbyshanreal-iOSon17/10/16.
//Copyright©2017年shanreal.LongZhenHao.Allrightsreserved.
//
#import"ViewController.h"
#import"TestBean.h"
@interfaceViewController()
@property(nonatomic,strong)UILabel*label;
@property(nonatomic,strong)UIButton*btn;
@property(nonatomic,strong)TestBean*bean;
@end
@implementationViewController
-(void)viewDidLoad{
[superviewDidLoad];
//Doanyadditionalsetupafterloadingtheview.
self.bean=[[TestBeanalloc]init];
[self.beansetValue:@"1"forKey:@"data"];
self.label=[[UILabelalloc]initWithFrame:CGRectMake(10,30,100,30)];
self.label.textColor=[UIColorblackColor];
self.label.text=[self.beanvalueForKey:@"data"];
[self.viewaddSubview:self.label];
self.btn=[[UIButtonalloc]initWithFrame:CGRectMake(10,100,200,30)];
[self.btnsetTitleColor:[UIColorblackColor]forState:UIControlStateNormal];
[self.btnsetTitle:@"chanagedata"forState:UIControlStateNormal];
[self.btnaddTarget:selfaction:@selector(clickAction)forControlEvents:UIControlEventTouchUpInside];
[self.viewaddSubview:self.btn];
}
-(void)viewWillAppear:(BOOL)animated{
[self.beanaddObserver:selfforKeyPath:@"data"options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOldcontext:NULL];
}
-(void)clickAction{
intdata=[[self.beanvalueForKey:@"data"]intValue]+1;
self.bean.data=[NSStringstringWithFormat:@"%d",data];
}
-(void)observeValueForKeyPath:(NSString*)keyPathofObject:(id)objectchange:(NSDictionary*)changecontext:(void*)context
{
if([keyPathisEqualToString:@"data"])
{
self.label.text=[self.beanvalueForKey:@"data"];
}
}
-(void)viewWillDisappear:(BOOL)animated{
[self.beanremoveObserver:selfforKeyPath:@"data"];
}
@end
#import
@interfaceTestBean:NSObject{
NSString*data;
}
@property(nonatomic,assign)intid;
@property(nonatomic,strong)NSString*data;
@end
#import"TestBean.h"
@implementationTestBean
@end
以上这篇iOS监听回调机制KVO实例就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持毛票票。