iOS几种传值方式

例如 ：第二个界面中的lable显示第一个界面textField中的文本

这就需要用到属性传值、block传值

那么第一个视图控制器如何获的第二个视图控制器的部分信息

例如：第一个界面中的lable显示第二个界面textField中的文本

这就需要使用代理传值

页面间传值有八大传值方式，下面我们就简单介绍下页面间传值的几种方式：

（一）属性传值

第二个界面中的lable显示第一个界面textField中的文本

首先我们建立一个RootViewControllers和一个DetailViewControllers，在DetailViewControllers中声明一个textString属性，用于接收传过来的字符串，

同时创建一个Lable用来显示传过的字符串

在RootViewControllers上引入DetailViewControllers同时声明一个textField属性用来输入字符串

然后在RootViewControllers上我们创建并添加一个button，当点击button时响应相应方法进行视图间的切换完成视图间的传值

二）Block传值

block传值也是从第二个界面给第一个界面传值

首先我们在DetailViewcontrollers的.h文件中，属性

在RootViewControllers的.m文件中，其他不变，在button的响应方法里我们为block属性赋值完成block传值

（三）代理传值

RootViewControllers页面push到DetailViewControllers页面，如果DetailViewControllers页面的信息想回传（回调）到RootViewControllers页面，用代理传值，其中DetailViewControllers定义协议和声明代理，RootViewControllers确认并实现代理，RootViewControllers作为DetailViewControllers的代理

首先在DetailViewControllers.h文件中我们创建协议方法

在DetailViewControllers的.m中我们判定代理对象存在时，为其绑定相应方法

RootViewControllers的.m文件中我们指定代理并让其执行代理的方法

（四）单例传值

单例传值（实现共享）

AppStatus.h  创建一个单例类 AppStatus

 1 #import <Foundation/Foundation.h> 2  3 @interface AppStatus : NSObject 4 { 5     NSString *_contextStr; 6 } 7  8 @property(nonatomic,retain)NSString *contextStr; 9 10 +(AppStatus *)shareInstance;11 12 @end

AppStatus.m

 1 #import "AppStatus.h" 2  3 @implementation AppStatus 4  5 @synthesize contextStr = _contextStr; 6  7 static AppStatus *_instance = nil; 8  9 +(AppStatus *)shareInstance10 {11     if (_instance == nil)12     {13         _instance = [[super alloc]init];14     }15     return _instance;16 }17 18 -(id)init19 {20     if (self = [super init])21     {22         23     }24     return self;25 }26 27 -(void)dealloc28 {29     [super dealloc];30 }31 32 @end

RootViewController.h

 1 #import "RootViewController.h" 2 #import "DetailViewController.h" 3 #import "AppStatus.h" 4  5 @interface RootViewController () 6  7 @end 8  9 @implementation RootViewController10 11 -(void)loadView12 {13     //核心代码 14     UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];15     btn.frame = CGRectMake(0, 0, 100, 30);16     [btn setTitle:@"Push" forState:0];17     [btn addTarget:self action:@selector(pushAction:) forControlEvents:UIControlEventTouchUpInside];18     [self.view addSubview:btn];19 }20 21 -(void)pushAction:(id)sender22 {23     tf = (UITextField *)[self.view viewWithTag:1000];24 25  //单例传值  将要传递的信息存入单例中（共享中）26   //  [[AppStatus shareInstance]setContextStr:tf.text]; 跟下面这种写法是等价的27     [AppStatus shareInstance].contextStr = tf.text;28     //导航push到下一个页面29     //pushViewController 入栈引用计数+1，且控制权归系统30     DetailViewController *detailViewController = [[DetailViewController alloc]init];31 32     //导航push到下一个页面33     [self.navigationController pushViewController:detailViewController animated:YES];34     [detailViewController release];35 } 36 37 @end

DetailViewController.h

1 #import <UIKit/UIKit.h>2 @protocol ChangeDelegate;//通知编译器有此代理3 4 @interface DetailViewController : UIViewController5 {6     UITextField *textField;7 }8 9 @end

DetailViewController.m

 1 #import "DetailViewController.h" 2 #import "AppStatus.h" 3  4 @interface DetailViewController () 5  6 @end 7  8 @implementation DetailViewController 9 10 @synthesize naviTitle = _naviTitle;11 12 -(void)loadView13 {14     self.view = [[[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, 480)]autorelease];15 16     //单例17     self.title = [AppStatus shareInstance].contextStr;18     textField = [[UITextField alloc]initWithFrame:CGRectMake(100, 100, 150, 30)];19     textField.borderStyle = UITextBorderStyleLine;20     [self.view addSubview:textField];21     [textField release];22 23     UIBarButtonItem *doneItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDonetarget:self action:@selector(doneAction:)];24     self.navigationItem.rightBarButtonItem = doneItem;25     [doneItem release];26 }27 28 //这个方法是执行多遍的  相当于刷新view29 -(void)viewWillAppear:(BOOL)animated30 {31     [super viewWillAppear:animated];32     tf = (UITextField *)[self.view viewWithTag:1000];33     tf.text = [AppStatus shareInstance].contextStr;34 }35 36 //pop回前一个页面37 -(void)doneAction:(id)sender38 {39     //单例传值40     [AppStatus shareInstance].contextStr = textField.text;41     [self.navigationController popToRootViewControllerAnimated:YES];42 } 

（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先决条件

A页面RootViewController.h

1 #import <UIKit/UIKit.h>2 #import "DetailViewController.h"3 @interface RootViewController : UIViewController<ChangeDelegate>4 {5     UITextField *tf;6 }7 @end 

A页面RootViewController.m

 1 #import "IndexViewController.h" 2 #import "DetailViewController.h" 3 #import "AppStatus.h" 4  5 @implementation IndexViewController 6  7 -(void)dealloc 8 { 9     [[NSNotificationCenter defaultCenter] removeObserver:self10                                                     name:@"CHANGE_TITLE" object:nil];11     [super dealloc];12 }13 14 -(id)init15 {16     if (self = [super init])17     {18         [[NSNotificationCenter defaultCenter] addObserver:self19                                                  selector:@selector(change:)20                                                      name:@"CHANGE_TITLE"21                                                    object:nil];22     }23     return self;24 }25 26 -(void)change:(NSNotification *)aNoti27 {28     // 通知传值29     NSDictionary *dic = [aNoti userInfo];30     NSString *str = [dic valueForKey:@"Info"];31     32     UITextField *tf =  (UITextField *)[self.view viewWithTag:1000];33     tf.text = str;34 }35  36 -(void)viewWillAppear:(BOOL)animated37 {38     [super viewWillAppear:animated];39     /*40     // 单例传值41     UITextField *tf =  (UITextField *)[self.view viewWithTag:1000];42     tf.text = [AppStatus shareInstance].contextStr;43     */44 }45 46 @end

DetailViewController.h

1 #import <UIKit/UIKit.h>2 @protocol ChangeDelegate;//通知编译器有此代理3 4 @interface DetailViewController : UIViewController5 {6     UITextField *textField;7 }8 @end

DetailViewController.m

 1 #import "DetailViewController.h" 2 #import "AppStatus.h" 3  4 @implementation DetailViewController 5 @synthesize naviTitle = _naviTitle; 6  7 -(void)loadView 8 { 9     UIBarButtonItem *doneItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDonetarget:self action:@selector(doneAction:)];10     self.navigationItem.rightBarButtonItem = doneItem;11     [doneItem release];12 }13 14 // pop回前一个页面15 -(void)doneAction:(id)sender16 {17 NSDictionary *dic = [NSDictionary dictionaryWithObject:textField.text forKey:@"Info"];18 19 [[NSNotificationCenter defaultCenter] postNotificationName:@"CHANGE_TITLE" object:nil userInfo:dic];20 21 [self.navigationController popViewControllerAnimated:YES];22 23 }