第二個視圖控制器如何獲取第一個視圖控制器的部分信息
這就需要用到屬性傳值、block傳值
那麼第一個視圖控制器如何獲的第二個視圖控制器的部分信息
例如:第一個界面中的lable顯示第二個界面textField中的文本
這就需要使用代理傳值
頁面間傳值有八大傳值方式,下面我們就簡單介紹下頁面間常用的五種傳值方式:
第二個界面中的lable顯示第一個界面textField中的文本
首先我們建立一個RootViewControllers和一個DetailViewControllers,在DetailViewControllers中聲明一個textString屬性,用於接收傳過來的字符串,
同時創建一個Lable用來顯示傳過的字符串
在RootViewControllers上引入DetailViewControllers同時聲明一個textField屬性用來輸入字符串
然後在RootViewControllers上我們創建並添加一個button,當點擊button時響應相應方法進行視圖間的切換完成視圖間的傳值
block傳值也是從第二個界面給第一個界面傳值
首先我們在DetailViewcontrollers的.h文件中,屬性
在RootViewControllers的.m文件中,其他不變,在button的響應方法裡我們為block屬性賦值完成block傳值
RootViewControllers頁面push到DetailViewControllers頁面,如果DetailViewControllers頁面的信息想回傳(回調)到RootViewControllers頁面,用代理傳值,其中DetailViewControllers定義協議和聲明代理,RootViewControllers確認並實現代理,RootViewControllers作為DetailViewControllers的代理
首先在DetailViewControllers.h文件中我們創建協議方法
在DetailViewControllers的.m中我們判定代理對象存在時,為其綁定相應方法
RootViewControllers的.m文件中我們指定代理並讓其執行代理的方法
單例傳值(實現共享)
AppStatus.h 創建一個單例類 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 //核心代碼 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 //單例傳值 將要傳遞的信息存入單例中(共享中) 26 // [[AppStatus shareInstance]setContextStr:tf.text]; 跟下面這種寫法是等價的 27 [AppStatus shareInstance].contextStr = tf.text; 28 //導航push到下一個頁面 29 //pushViewController 入棧引用計數+1,且控制權歸系統 30 DetailViewController *detailViewController = [[DetailViewController alloc]init]; 31 32 //導航push到下一個頁面 33 [self.navigationController pushViewController:detailViewController animated:YES]; 34 [detailViewController release]; 35 } 36 37 @end
DetailViewController.h
1 #import <UIKit/UIKit.h> 2 @protocol ChangeDelegate;//通知編譯器有此代理 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 //單例 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 //這個方法是執行多遍的 相當於刷新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回前一個頁面 37 -(void)doneAction:(id)sender 38 { 39 //單例傳值 40 [AppStatus shareInstance].contextStr = textField.text; 41 [self.navigationController popToRootViewControllerAnimated:YES]; 42 }
誰要監聽值的變化,誰就注冊通知 特別要注意,通知的接受者必須存在這一先決條件
A頁面RootViewController.h
1 #import <UIKit/UIKit.h> 2 #import "DetailViewController.h" 3 @interface RootViewController : UIViewController<ChangeDelegate> 4 { 5 UITextField *tf; 6 } 7 @end
A頁面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 // 通知傳值 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 // 單例傳值 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;//通知編譯器有此代理 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回前一個頁面 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 }