iOS页面间传值的方式（Delegate/NSNotification/Block/NSUserDefault/单例）

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

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1.//SecondViewController.h

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1.@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

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1.//RootViewController.m

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1.- (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          

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1. 

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1.//SecondViewController.h

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1.@protocol secondViewDelegate

2.-(void)showName:(NSString *)nameString;

3.@end

设置代理(为防止循环引用，此处采用了weak)

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1. 

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1.//SecondViewController.h

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1.@interface SecondViewController : UIViewController

2.@property (nonatomic, weak)id<secondViewDelegate> delegate;

3.@property (nonatomic, copy) ablock block;

4.@end

   调用

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01.//SecondViewController.m

02.- (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  

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1.//RootViewController.m

2.-(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：

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01.//SecondViewController.m

02.- (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：

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1.//RootViewController.m

2.- (void)viewDidLoad

3.{

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：

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1.//RootViewController.m

2.-(void)dealloc{

3.[[NSNotificationCenter defaultCenter] removeObserver:self];

4.}

 调用，显示

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1.//RootViewController.m

2. 

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

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1.//SecondViewController.h

2.typedef void (^ablock)(NSString *str);

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1.//SecondViewController.h

2. 

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

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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

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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

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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

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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

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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

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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

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01.//

02.//  DataSource.h

03.//  TestCallBack

04.//

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 : NSObject

12.@property (nonatomic, strong) NSString *myName;

13.+(DataSource*)sharedDataSource;

14.@end 

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01.//

02.//  DataSource.m

03.//  TestCallBack

04.//

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 DataSource

12.+(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.@end