iOS 頁面間幾種傳值方式(屬性,代理,block,單例,通知),iosblock
第二個視圖控制器如何擷取第一個視圖控制器的部分資訊
例如 :第二個介面中的lable顯示第一個介面textField中的文本
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資訊
例如:第一個介面中的lable顯示第二個介面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:
(一)屬性傳值
第二個介面中的lable顯示第一個介面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串,
同時建立一個Lable用來顯示傳過的字串
在RootViewControllers上引入DetailViewControllers同時聲明一個textField屬性用來輸入字串
然後在RootViewControllers上我們建立並添加一個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
(二)Block傳值
block傳值也是從第二個介面給第一個介面傳值
首先我們在DetailViewcontrollers的.h檔案中,屬性
在RootViewControllers的.m檔案中,其他不變,在button的回應程式法裡我們為block屬性賦值完成block傳值
(三)代理傳值
RootViewControllers頁面push到DetailViewControllers頁面,如果DetailViewControllers頁面的資訊想回傳(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檔案中我們建立協議方法
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檔案中我們指定代理並讓其執行代理的方法
(四)單例傳值
單例傳值(實現共用)
AppStatus.h 建立一個單例類 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 *)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)sender22 {23 tf = (UITextField *)[self.view viewWithTag:1000];24 25 //單例傳值 將要傳遞的資訊存入單例中(共用中)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 : 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 //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 相當於重新整理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回前一個頁面37 -(void)doneAction:(id)sender38 {39 //單例傳值40 [AppStatus shareInstance].contextStr = textField.text;41 [self.navigationController popToRootViewControllerAnimated:YES];42 }
(五)通知傳值
誰要監聽值的變化,誰就註冊通知 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: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)animated37 {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 : 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回前一個頁面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 }