(-)属性传值
属性传值(场景)一般用于正向传值,即第一个界面传值给第二个界面
属性传值是这几大传值中最简单的传值方式只需要要记住两点:
1.要在接收值的界面(ViewController_2)中声明属性即文中: aString
2.要在跳转界面的同时将要传的赋值给下个控制器对象的属性即文中的这个操作: secondVc.aString =textF.text;
(二)Block传值
block传值(场景)一般用于逆向传值,即第二个界面传值给第一个界面
block对比属性传值,我们也需要记住两点:
1.要在第二个界面(SecondViewController.h)定义一个Block:
#import
typedef void (^PushBlock)(NSString*);
@interface SecondViewController : UIViewController
@property (nonatomic,strong)PushBlock pushValueString;
@endpushValueString;
2.要在第一个界面(FirstViewController.m)跳转第二个界面的方法中我们为block属性赋值完成block传值:
-(void)PushClick:(UIButton*)sender{SecondViewController * secondVc = [[SecondViewController alloc]initsecondVc.pushValueString = ^(NSString*str){ textF.text =str;} ;[self.navigationController pushViewController:secondVc animated:YES];}
Block传值完整代码如下:
FirstViewController
#import"FirstViewController.h"#import"SecondViewController.h"@interfaceFirstViewController(){UITextField* textF;}@end@implementationFirstViewController- (void)viewDidLoad {[superviewDidLoad];self.view.backgroundColor =[UIColorwhiteColor];[selfcreatUI];}-(void)creatUI{textF = [[UITextFieldalloc]init];textF.frame =CGRectMake(0,100,self.view.frame.size.width,30);textF.borderStyle =UITextBorderStyleRoundedRect;[self.view addSubview:textF];UIButton* PushBtn = [UIButtonbuttonWithType:(UIButtonTypeSystem)];PushBtn.frame =CGRectMake(0,140,self.view.frame.size.width,30);[PushBtn setTitle:@"Push"forState:(UIControlStateNormal)];[PushBtn addTarget:selfaction:@selector(PushClick:) forControlEvents:(UIControlEventTouchUpInside)];[self.view addSubview:PushBtn];}//跳转下个界面点击事件-(void)PushClick:(UIButton*)sender{SecondViewController * secondVc = [[SecondViewController alloc]init];//核心代码为block属性赋值secondVc.pushValueString = ^(NSString*str){ textF.text =str;} ;[self.navigationController pushViewController:secondVc animated:YES];}
SecondViewController
#importtypedefvoid(^PushBlock)(NSString*);@interfaceSecondViewController:UIViewController@property(nonatomic,strong)PushBlock pushValueString;@end#import"SecondViewController.h"@interfaceSecondViewController(){UITextField* textF;NSString* textFString;}@end@implementationSecondViewController- (void)viewDidLoad {[superviewDidLoad];self.view.backgroundColor = [UIColorwhiteColor];textF = [[UITextFieldalloc]init];textF.frame =CGRectMake(0,100,self.view.frame.size.width,30);textF.borderStyle =UITextBorderStyleRoundedRect;[self.view addSubview:textF];UIButton* Backbtn = [UIButtonbuttonWithType:(UIButtonTypeSystem)];Backbtn.frame =CGRectMake(0,140,self.view.frame.size.width,30);[Backbtn addTarget:selfaction:@selector(backClick:) forControlEvents:(UIControlEventTouchUpInside)];[Backbtn setTitle:@"back"forState:(UIControlStateNormal)];[self.view addSubview:Backbtn];}//返回第一个界面并将值带入-(void)backClick:(UIButton*)sender{//核心代码_pushValueString(textF.text);[self.navigationController popViewControllerAnimated:YES];}
(三)代理传值
代理传值(场景)一般用于逆向传值,即第二个界面传值给第一个界面
FirstViewController页面push到SecondViewController页面,如果SecondViewController页面的信息想回传(回调)到FirstViewController页面,用代理传值，其中SecondViewController定义协议和声明代理,FirstViewController确认并实现代理,FirstViewController作为SecondViewController的代理
对于代理传值我们要记住如下记步操作:
第一步:首先,在SecondViewController.h中
(1).定义协议
(2).设置协议中的方法
(3).声明代理
然后,在SecondViewController.m中
(1).为其绑定相应方法
第二步:在FirstViewController.m中
(1).设置代理
(2).服从协议
完整代理传值代码如下:
SecondViewController
//首先在SecondViewController.h中创建协议方法#import@classSecondViewController;//定义协议@protocolPushValueDelegate@optional//设置协议中的方法-(void)viewController:(SecondViewController*)ViewController didPushVlaueWithInfo:(id)info;@end@interfaceSecondViewController:UIViewController//声明代理@property(nonatomic,assign)iddelegate;@end//然后,在SecondViewController.m中我们判定代理对象存在时，为其绑定相应方法#import"SecondViewController.h"@interfaceSecondViewController(){UITextField* textF;NSString* textFString;}@end@implementationSecondViewController-(void)viewWillDisappear:(BOOL)animated{//设置视图将要消失时.通过代理传值//判断代理是否存在,并且设置代理能够响应代理方法时,才执行代理方法if(self.delegate && [self.delegate respondsToSelector:@selector(viewController:didPushVlaueWithInfo:)]) { [self.delegate viewController:selfdidPushVlaueWithInfo:textF.text];}}- (void)viewDidLoad {[superviewDidLoad];self.view.backgroundColor = [UIColorredColor];textF = [[UITextFieldalloc]init];textF.frame =CGRectMake(0,100,self.view.frame.size.width,30);textF.borderStyle =UITextBorderStyleRoundedRect;[self.view addSubview:textF];}
FirstViewController
#import"FirstViewController.h"#import"SecondViewController.h"//服从协议@interfaceFirstViewController(){UITextField* textF;}@end@implementationFirstViewController- (void)viewDidLoad {[superviewDidLoad];self.view.backgroundColor =[UIColorwhiteColor];[selfcreatUI]; }-(void)creatUI{textF = [[UITextFieldalloc]init];textF.frame =CGRectMake(0,100,self.view.frame.size.width,30);textF.borderStyle =UITextBorderStyleRoundedRect;[self.view addSubview:textF];UIButton* PushBtn = [UIButtonbuttonWithType:(UIButtonTypeSystem)];PushBtn.frame =CGRectMake(0,140,self.view.frame.size.width,30);[PushBtn setTitle:@"Push"forState:(UIControlStateNormal)];[PushBtn addTarget:selfaction:@selector(PushClick:) forControlEvents:(UIControlEventTouchUpInside)];[self.view addSubview:PushBtn];}-(void)PushClick:(UIButton*)sender{SecondViewController * secondVc = [[SecondViewController alloc]init];//设置代理secondVc.delegate =self;[self.navigationController pushViewController:secondVc animated:YES];}//实现代理方法-(void)viewController:(SecondViewController*)ViewController didPushVlaueWithInfo:(id)info{textF.text = info;}
(四)单例传值
单例可以保证某个类的实例在程序中是唯一的，便于进行资源和数据的共享。
单例的实现:
（1）新建一个普通的类，假设名字为People 在People.h中声明一个类方法，到时候使用该类方法（注意：一定是类方法，而不是实例方法）可以创建该类的唯一的一个实例
#import"Peopel.h"@implementationPeople{NSString*_eat; }@property(nonatomic,retain)NSString*eat;+(Peopel*)shareInstance;@end
（2）在Peopel .m中需要实现sharedInstance方法和你其他的业务逻辑
#import "Peopel.h"
//static声明一个类的静态实例;
static Peopelinstrance = nil;
@implementation Peopel
//使用类方法生成这个类唯一的实例
+(Peopel
)shareInstance{
if(instrance ==nil) { instrance = [[superalloc]init]; }returninstrance;}@end
注意：一定要声明一个static的静态变量。以后创建类的唯一实例就使用sharedInstance方法，而不是使用alloc ,init.
下面为单例传值的简单使用(完整代码):
FirstViewController
#import"FirstViewController.h"#import"SecondViewController.h"#import"Peopel.h"@interfaceFirstViewController(){UITextField* textF;}@end@implementationFirstViewController- (void)viewDidLoad {[superviewDidLoad];self.view.backgroundColor =[UIColorwhiteColor];[selfcreatUI];}//接收由第二个界面pop回时textF里的数据值-(void)viewWillAppear:(BOOL)animated{[superviewWillAppear:animated];textF.text=[Peopel shareInstance].eat;}-(void)creatUI{textF = [[UITextFieldalloc]init];textF.frame =CGRectMake(0,100,self.view.frame.size.width,30);textF.borderStyle =UITextBorderStyleRoundedRect;[self.view addSubview:textF];UIButton* PushBtn = [UIButtonbuttonWithType:(UIButtonTypeSystem)];PushBtn.frame =CGRectMake(0,140,self.view.frame.size.width,30);[PushBtn setTitle:@"Push"forState:(UIControlStateNormal)];[PushBtn addTarget:selfaction:@selector(PushClick:) forControlEvents:(UIControlEventTouchUpInside)];[self.view addSubview:PushBtn];}-(void)PushClick:(UIButton*)sender{//跳转下个界面的同时为单例属性赋值[[Peopel shareInstance]setEat:textF.text];SecondViewController * secondVc = [[SecondViewController alloc]init];[self.navigationController pushViewController:secondVc animated:YES]; }
SecondViewController
#import"SecondViewController.h"#import"Peopel.h"@interfaceSecondViewController(){UITextField* textF;NSString* textFString;}@end@implementationSecondViewController-(void)viewWillDisappear:(BOOL)animated{}-(void)viewWillAppear:(BOOL)animated{[superviewWillAppear:animated];textF.text = [Peopel shareInstance].eat;}- (void)viewDidLoad {[superviewDidLoad];self.view.backgroundColor = [UIColorredColor];textF = [[UITextFieldalloc]init];textF.frame =CGRectMake(0,100,self.view.frame.size.width,30);textF.borderStyle =UITextBorderStyleRoundedRect;textF.text = [Peopel shareInstance].eat;[self.view addSubview:textF];//返回按钮UIButton* Backbtn = [UIButtonbuttonWithType:(UIButtonTypeSystem)];Backbtn.frame =CGRectMake(0,140,self.view.frame.size.width,30);[Backbtn addTarget:selfaction:@selector(backClick:) forControlEvents:(UIControlEventTouchUpInside)];[Backbtn setTitle:@"back"forState:(UIControlStateNormal)];[self.view addSubview:Backbtn];}-(void)backClick:(UIButton*)sender{//返回时为单例属性赋值[Peopel shareInstance].eat = textF.text;[self.navigationController popViewControllerAnimated:YES];}
(五)通知传值
谁要监听值的变化，谁就注册通知 特别要注意，通知的接受者必须存在这一条件
1、注册通知
2、通知中心发送一条消息通知，其中name前后一定要一样
3、实现通知中心内部的方法，并实现传值
4、消息发送完，要移除掉。（页面将要消失的时候）
通知传值的简单代码如下:
代码为第二个界面传值到第一个界面的实现:
FirstViewController
#import"FirstViewController.h"#import"SecondViewController.h"@interfaceFirstViewController(){UITextField* textF;}@end@implementationFirstViewController- (void)viewDidLoad {[superviewDidLoad];self.view.backgroundColor =[UIColorwhiteColor];[selfcreatUI];/**
adObserver:注册监听者,一般都是控制器本身去监听一个通知
selector :当监听到通知的时候执行的方法
name :通知的名字,要和发送的通知的对象的名字一致
object: nil
*///注册监听者[[NSNotificationCenterdefaultCenter]addObserver:selfselector:@selector(ChangeTextFText:) name:@"ChangeValue"object:nil];}-(void)ChangeTextFText:(NSNotification*)notification{NSDictionary* dic = notification.userInfo;NSLog(@"%@",dic);textF.text = dic[@"Value"];}-(void)creatUI{textF = [[UITextFieldalloc]init];textF.frame =CGRectMake(0,100,self.view.frame.size.width,30);textF.borderStyle =UITextBorderStyleRoundedRect;[self.view addSubview:textF];UIButton* PushBtn = [UIButtonbuttonWithType:(UIButtonTypeSystem)];PushBtn.frame =CGRectMake(0,140,self.view.frame.size.width,30);[PushBtn setTitle:@"Push"forState:(UIControlStateNormal)];[PushBtn addTarget:selfaction:@selector(PushClick:) forControlEvents:(UIControlEventTouchUpInside)];[self.view addSubview:PushBtn];}-(void)PushClick:(UIButton*)sender{SecondViewController * secondVc = [[SecondViewController alloc]init];[self.navigationController pushViewController:secondVc animated:YES];}//移除控制器上所有监听的通知-(void)dealloc{[[NSNotificationCenterdefaultCenter]removeObserver:self];}
SecondViewController
#import"SecondViewController.h"@interfaceSecondViewController(){UITextField* textF;}@end@implementationSecondViewController-(void)viewWillAppear:(BOOL)animated{[superviewWillAppear:animated];}- (void)viewDidLoad {[superviewDidLoad];self.view.backgroundColor = [UIColorredColor];textF = [[UITextFieldalloc]init];textF.frame =CGRectMake(0,100,self.view.frame.size.width,30);textF.borderStyle =UITextBorderStyleRoundedRect;[self.view addSubview:textF];UIButton* Backbtn = [UIButtonbuttonWithType:(UIButtonTypeSystem)];Backbtn.frame =CGRectMake(0,140,self.view.frame.size.width,30);[Backbtn addTarget:selfaction:@selector(backClick:) forControlEvents:(UIControlEventTouchUpInside)];[Backbtn setTitle:@"back"forState:(UIControlStateNormal)];[self.view addSubview:Backbtn];}-(void)backClick:(UIButton*)sender{//发送通知[[NSNotificationCenterdefaultCenter]postNotificationName:@"ChangeValue"object:niluserInfo:@{@"Value":textF.text}];[self.navigationController popViewControllerAnimated:YES];}
