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iOS页面间传值的方式（NSUserDefault/Delegate/NSNotification/Block/单例）
实现了以下iOS页面间传值：1.委托delegate方式；2.通知notification方式；3.block方式；4.UserDefault或者文件方式；5.单例模式方式；6.通过设置属性，实现页面间传值
在iOS开发中，我们经常会遇到页面间跳转传值的问题，现归纳总结一下：
情况1：A页面跳转到B页面
方法：
在B页面的控制器中，编写对应的属性，在A页面跳转到B页面的地方，给B的属性赋值即可
1.//SecondViewController.h1.@property(nonatomic) NSInteger flag;//当前系统标示（0：其他传值方式；1：block传值方式）在A页面的试图控制器中
1.//RootViewController.m1.- (IBAction)showSecondView:(id)sender {2.SecondViewController *second = [[SecondViewController alloc] initWithNibName:@‘SecondViewController‘bundle:nil];3.second.delegate = self;4.second.flag = 0;5.[self presentViewController:second animated:YES completion:nil];6.}情况2：A页面跳转到B页面，B页面再跳转回A页面
主流方案：
（1）通过委托delegate的方式实现
设置协议及方法
1. 1.//SecondViewController.h1.@protocol secondViewDelegate2.-(void)showName:(NSString *)nameString;3.@end设置代理(为防止循环引用，此处采用了weak)
1. 1.//SecondViewController.h1.@interface SecondViewController : UIViewController2.@property (nonatomic, weak)id<secondViewDelegate> delegate;3.@property (nonatomic, copy) ablock block;4.@end调用
01.//SecondViewController.m02.- (IBAction)delegateMethod:(id)sender {03.if ([self notEmpty]) {04.[self.delegate showName:self.nameTextField.text];05.[self dismissViewControllerAnimated:YES completion:nil];06.}else{07.[self showAlert];08.}09.}
显示
1.//RootViewController.m2.-(void)showName:(NSString
*)nameString{3.self.nameLabel.text
= nameString;4.}最重要也是最容易忽略的，就是一定要设置delegate的指向。
（2）通过通知notification的方式实现
在B页面的控制器中，发送通知：
01.//SecondViewController.m02.-
(IBAction)notificationMethod:(id)sender {03.if ([self
notEmpty]) {04.[[NSNotificationCenter
defaultCenter] postNotificationName:@‘ChangeNameNotification‘ object:self
userInfo:@{@‘name‘:self.nameTextField.text}];05.[self
dismissViewControllerAnimated:YES completion:nil];06.}else{07.[self
showAlert];08.}09.}在A页面的控制器中，注册通知：
1.//RootViewController.m2.-
(void)viewDidLoad3.{4.[super viewDidLoad];5.//
Do any additional setup after loading the view from its nib.6.[[NSNotificationCenter
defaultCenter] addObserver:self selector:@selector(ChangeNameNotification:)
name:@‘ChangeNameNotification‘ object:nil];7.}当我们不使用时，要记得删掉通知：
1.//RootViewController.m2.-(void)dealloc{3.[[NSNotificationCenter
defaultCenter] removeObserver:self];4.}调用，显示
1.//RootViewController.m2. 3.-(void)ChangeNameNotification:(NSNotification*)notification{4.NSDictionary
*nameDictionary = [notification userInfo];5.self.nameLabel.text
= [nameDictionary objectForKey:@‘name‘];6.}（3）block方式实现
block介绍:http://blog.csdn.net/totogo2010/article/details/7839061
链接一篇描述block回调挺有意思的文章： http://blog.csdn.net/mobanchengshuang/article/details/11751671
分析：
在B试图控制器中，定义一个block，参数为字符串
1.//SecondViewController.h2.typedef void (^ablock)(NSString
*str);1.//SecondViewController.h2. 3.@property (nonatomic,
copy) ablock block;在B试图控制器中，当输入名字，点击对应的确定按钮后
01.-
(IBAction)blockMethod:(id)sender {02.if ([self
notEmpty]) {03.if (self.block)
{04.self.block(self.nameTextField.text);05.[self
dismissViewControllerAnimated:YES completion:nil];06.}07.}else{08.[self
showAlert];09.}10.}在A试图显示，回调block
1.-
(IBAction)showSecondWithBlock:(id)sender {2.SecondViewController
*second = [[SecondViewController alloc] initWithNibName:@‘SecondViewController‘bundle:nil];3.[self
presentViewController:second animated:YES completion:nil];4.second.block
= ^(NSString *str){5.self.nameLabel.text
= str;6.};7.}在查阅资料的过程中，我还看到了以下几种方案：
（1）使用SharedApplication,定义一个变量来传递（感觉和单例的方式一样）
（2）使用文件，或者NSUserdefault来传递
01.//通过文件或者UserDefault方式存值(感觉不太适合此类传值，如果要用文件或者UserDefault方式存值的话，可以考虑此方式)02.-
(IBAction)userDefaultMethod:(id)sender {03.if ([self
notEmpty]) {04.[[NSUserDefaults
standardUserDefaults] setObject:self.nameTextField.text forKey:@‘myNameText‘];05.[self
dismissViewControllerAnimated:YES completion:nil];06.}else{07.[self
showAlert];08.}09.}在A试图控制器显示
01.-(void)viewDidAppear:(BOOL)animated{02.[super viewDidAppear:animated];03.//如果想测试通过UserDefault方式传值或者通过单例方式传值，取消以下注释即可04./*05.if
([[[NSUserDefaults standardUserDefaults] objectForKey:@‘myNameText‘] length] != 0) {06.self.nameLabel.text
= [[NSUserDefaults standardUserDefaults] objectForKey:@‘myNameText‘];07.[[NSUserDefaults
standardUserDefaults] setObject:@‘‘ forKey:@‘myNameText‘];08.}09.DataSource
*dataSource = [DataSource sharedDataSource];10.if
([dataSource.myName length] != 0) {11.self.nameLabel.text
= dataSource.myName;12.dataSource.myName
= @‘‘;13.}14.*/15.}（3）通过一个单例的class来传递
B试图控制器
01.//通过单例方式传值(感觉不太适合此类传值，如果要用单例方式传值的话，可以考虑此方式)02.-
(IBAction)singletonMethod:(id)sender {03.if ([self
notEmpty]) {04.DataSource
*dataSource = [DataSource sharedDataSource];05.dataSource.myName
= self.nameTextField.text;06.[self
dismissViewControllerAnimated:YES completion:nil];07.}else{08.[self
showAlert];09.}10.}A试图控制器显示
01.-(void)viewDidAppear:(BOOL)animated{02.[super viewDidAppear:animated];03.//如果想测试通过UserDefault方式传值或者通过单例方式传值，取消以下注释即可04./*05.if
([[[NSUserDefaults standardUserDefaults] objectForKey:@‘myNameText‘] length] != 0) {06.self.nameLabel.text
= [[NSUserDefaults standardUserDefaults] objectForKey:@‘myNameText‘];07.[[NSUserDefaults
standardUserDefaults] setObject:@‘‘ forKey:@‘myNameText‘];08.}09.DataSource
*dataSource = [DataSource sharedDataSource];10.if
([dataSource.myName length] != 0) {11.self.nameLabel.text
= dataSource.myName;12.dataSource.myName
= @‘‘;13.}14.*/15.}16.@end这里面用到了单例模式，编写了DataSource这个类，存放数据
01.//02.//
DataSource.h03.//
TestCallBack04.//05.//
Created by csdc-iMac on 14-7-17.06.//
Copyright (c) 2014年 JuneWang. All rights reserved.07.//08. 09.#import <Foundation/Foundation.h>10. 11.@interface DataSource
: NSObject12.@property (nonatomic,
strong) NSString *myName;13.+(DataSource*)sharedDataSource;14.@end 01.//02.//
DataSource.m03.//
TestCallBack04.//05.//
Created by csdc-iMac on 14-7-17.06.//
Copyright (c) 2014年 JuneWang. All rights reserved.07.//08. 09.#import ‘DataSource.h‘10. 11.@implementation DataSource12.+(DataSource
*)sharedDataSource{13.static DataSource
*dataSource = nil;14.static dispatch_once_t
once;15.dispatch_once(&once,
^{16.dataSource
= [DataSource new];17.});18.return dataSource;19.}20.@endiOS页面间传值的方式（Delegate/NSNotification/Block/NSUserDefault/单例）
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原文地址：http://www.cnblogs.com/sunkaifeng/p/5086727.html
