页面传值的五种方法+1
第二个视图控制器如何获取第一个视图控制器的部分信息
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常用的五种传值方式:
(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
//属性反向传值(不常用)
#pragma mark 2. - 属性:逆向传值 /** *ViewController *firstVC = [self.navigationController.childViewControllers objectAtIndex:0]; * 1. 通过 [self.navigationController.childViewControllers objectAtIndex:0] 找到要跳转的 vc 利用属性逆向传值,0代表调回第一个viewcontroller * 2. firstVC .h声明属性@property()nsstring *string; * 3. 当前vc的string给firstVC.string(firstVC.string = string); * 4. [self.navigationController popToViewController:firstVC animated:YES]; */
(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 *)shareInstance 10 { 11 if (_instance == nil) 12 { 13 _instance = [[super alloc]init]; 14 } 15 return _instance; 16 } 17 18 -(id)init 19 { 20 if (self = [super init]) 21 { 22 23 } 24 return self; 25 } 26 27 -(void)dealloc 28 { 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 RootViewController 10 11 -(void)loadView 12 { 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)sender 22 { 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 : UIViewController
5 {
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)loadView 13 { 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view 29 -(void)viewWillAppear:(BOOL)animated 30 { 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)sender 38 { 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:self 10 name:@"CHANGE_TITLE" object:nil]; 11 [super dealloc]; 12 } 13 14 -(id)init 15 { 16 if (self = [super init]) 17 { 18 [[NSNotificationCenter defaultCenter] addObserver:self 19 selector:@selector(change:) 20 name:@"CHANGE_TITLE" 21 object:nil]; 22 } 23 return self; 24 } 25 26 -(void)change:(NSNotification *)aNoti 27 { 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)animated 37 { 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 : UIViewController
5 {
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)sender 16 { 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 }