Value Transfer Between iOS pages (Delegate/NSNotification/Block/NSUserDefault/Singleton), iosnsnotification

Value Transfer Between iOS pages (Delegate/NSNotification/Block/NSUserDefault/Singleton), iosnsnotification

 

How to pass values between iOS pages (NSUserDefault/Delegate/NSNotification/Block/Singleton)

The following values are passed between iOS pages: 1. delegate the delegate method; 2. notification method; 3. block Method; 4. userDefault or file method; 5. singleton mode; 6. set Properties to pass values between pages

During iOS development, we often encounter the issue of jump between pages to transfer values. Here we will summarize:

Scenario 1: page A jumps to page B

Method:

In the controller of page B, write the corresponding attributes, jump to the location of page B on page A, and assign values to the attributes of page B.

//SecondViewController.h

@ Property (nonatomic) NSInteger flag; // The Current System ID (0: other value passing methods; 1: block Value passing methods)

In the attempt controller of page

 

//RootViewController.m

- (IBAction)showSecondView:(id)sender {    SecondViewController *second = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];    second.delegate = self;    second.flag = 0;    [self presentViewController:second animated:YES completion:nil];}

 

Case 2: page A jumps to page B, and page B jumps back to page

Mainstream solutions:

(1) implemented by entrusting delegate

 

SET protocols and Methods

//SecondViewController.h

@protocol secondViewDelegate-(void)showName:(NSString *)nameString;@end

 

Set proxy (to prevent loop reference, weak is used here)

 

//SecondViewController.h

@interface SecondViewController : UIViewController@property (nonatomic, weak)id<secondViewDelegate> delegate;@property (nonatomic, copy) ablock block;@end

Call

//SecondViewController.m
- (IBAction)delegateMethod:(id)sender {    if ([self notEmpty]) {        [self.delegate showName:self.nameTextField.text];        [self dismissViewControllerAnimated:YES completion:nil];    }else{        [self showAlert];    }}

Display

//RootViewController.m
-(void)showName:(NSString *)nameString{    self.nameLabel.text = nameString;}

 

The most important and easy to ignore is to set the delegate point.

(2) notification

In the controller of page B, send a notification:

//SecondViewController.m- (IBAction)notificationMethod:(id)sender {    if ([self notEmpty]) {        [[NSNotificationCenter defaultCenter] postNotificationName:@"ChangeNameNotification" object:self userInfo:@{@"name":self.nameTextField.text}];        [self dismissViewControllerAnimated:YES completion:nil];    }else{        [self showAlert];    }}

 

Register the notification in the Controller on page:

//RootViewController.m- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view from its nib.    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(ChangeNameNotification:) name:@"ChangeNameNotification" object:nil];}

Remember to delete the notification when we do not use it:

//RootViewController.m-(void)dealloc{    [[NSNotificationCenter defaultCenter] removeObserver:self];}

 

Call, display

//RootViewController.m-(void)ChangeNameNotification:(NSNotification*)notification{    NSDictionary *nameDictionary = [notification userInfo];    self.nameLabel.text = [nameDictionary objectForKey:@"name"];}

 

(3) block implementation

Block Introduction: http://blog.csdn.net/totogo2010/article/details/7839061

A very interesting article describing block callback: http://blog.csdn.net/mobanchengshuang/article/details/11751671

Analysis:

In B's attempt to control a block, the parameter is a string

//SecondViewController.htypedef void (^ablock)(NSString *str);

//SecondViewController.h@property (nonatomic, copy) ablock block;

In B's attempt controller, after entering the name and clicking the corresponding OK button

- (IBAction)blockMethod:(id)sender {    if ([self notEmpty]) {        if (self.block) {            self.block(self.nameTextField.text);            [self dismissViewControllerAnimated:YES completion:nil];        }    }else{        [self showAlert];    }}

When A tries to display, the callback block

- (IBAction)showSecondWithBlock:(id)sender {    SecondViewController *second = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];    [self presentViewController:second animated:YES completion:nil];    second.block = ^(NSString *str){        self.nameLabel.text = str;    };}

 

 

I also saw the following solutions when I checked the materials:

(1) Use SharedApplication to define a variable for transmission (feeling the same way as Singleton)

 

(2) Use a file or NSUserdefault to pass

 

// Store values in the file or UserDefault mode (this method is not suitable for storing values in the file or UserDefault mode)-(IBAction) userDefaultMethod :( id) sender {if ([self notEmpty]) {[[NSUserDefaults standardUserDefaults] setObject: self. nameTextField. text forKey: @ "myNameText"]; [self dismissViewControllerAnimated: YES completion: nil];} else {[self showAlert];}

When A tries to display controller

-(Void) viewDidAppear :( BOOL) animated {[super viewDidAppear: animated]; // if you want to test data passing through UserDefault or using Singleton, cancel the following comments to/* if ([[NSUserDefaults standardUserDefaults] objectForKey: @ "myNameText"] length]! = 0) {self. nameLabel. text = [[NSUserDefaults standardUserDefaults] objectForKey: @ "myNameText"]; [[NSUserDefaults standardUserDefaults] setObject: @ "forKey: @" myNameText "];} dataSource * dataSource = [DataSource sharedDataSource]; if ([dataSource. myName length]! = 0) {self. nameLabel. text = dataSource. myName; dataSource. myName = @"";}*/}

 

(3) passing through a singleton class

B tries to Controller

// Pass the value through the singletonMethod (this method is not suitable for this type of value transfer. If you want to use the singletonMethod, you can consider this method)-(IBAction) singletonMethod :( id) sender {if ([self notEmpty]) {DataSource * dataSource = [DataSource sharedDataSource]; dataSource. myName = self. nameTextField. text; [self dismissViewControllerAnimated: YES completion: nil];} else {[self showAlert] ;}}

A tries to display the Controller

-(Void) viewDidAppear :( BOOL) animated {[super viewDidAppear: animated]; // if you want to test data passing through UserDefault or using Singleton, cancel the following comments to/* if ([[NSUserDefaults standardUserDefaults] objectForKey: @ "myNameText"] length]! = 0) {self. nameLabel. text = [[NSUserDefaults standardUserDefaults] objectForKey: @ "myNameText"]; [[NSUserDefaults standardUserDefaults] setObject: @ "forKey: @" myNameText "];} dataSource * dataSource = [DataSource sharedDataSource]; if ([dataSource. myName length]! = 0) {self. nameLabel. text = dataSource. myName; dataSource. myName = @ "";} */} @ end

The Singleton mode is used here. The DataSource class is compiled to store data.

/// DataSource. h // TestCallBack /// Created by csdc-iMac on 14-7-17. // Copyright (c) 2014 JuneWang. all rights reserved. // # import <Foundation/Foundation. h> @ interface DataSource: NSObject @ property (nonatomic, strong) NSString * myName; + (DataSource *) sharedDataSource; @ end

 

/// DataSource. m // TestCallBack /// Created by csdc-iMac on 14-7-17. // Copyright (c) 2014 JuneWang. all rights reserved. // # import "DataSource. h "@ implementation DataSource + (DataSource *) sharedDataSource {static DataSource * dataSource = nil; static dispatch_once_t once; dispatch_once (& once, ^ {dataSource = [DataSource new];}); return dataSource;} @ end

 

Program running

A View:

B View

When you enter A name and click the corresponding confirmation button, the system returns to view A and displays the name entered in view B.

 

I wish you a good time. please correct me if you have any other or incorrect solutions.

If it is not detailed, you can use the source code analysis.

 

Reference: http://blog.csdn.net/cocoarannie/article/details/11857141

Http://www.cnblogs.com/heri/archive/2013/03/18/2965815.html

 

Source Code address: https://github.com/wangtao169447/PassValue

Reprinted please indicate the source: http://www.cnblogs.com/JuneWang/p/3850859.html

The block in iOS can replace delegate

Yes !, If the value is simple, block is good.

How does one pass the value on the IOS page?

Little cainiao, 1 custom cell, add attribute to cell

2. delegate for Minor Use

3 block

A demo is required for this broken object?