iOS页面间传值的方式（Delegate/NSNotification/Block/NSUserDefault/单例）

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mb2928593829 2022-07-28 12:05:58

iOS页面间传值的方式（NSUserDefault/Delegate/NSNotification/Block/单例）
实现了以下iOS页面间传值：1.委托delegate方式；2.通知notification方式；3.block方式；4.UserDefault或者文件方式；5.单例模式方式；6.通过设置属性，实现页面间传值
在iOS开发中，我们经常会遇到页面间跳转传值的问题，现归纳总结一下：
情况1：A页面跳转到B页面
方法：
在B页面的控制器中，编写对应的属性，在A页面跳转到B页面的地方，给B的属性赋值即可

1.//SecondViewController.h
1.@property(nonatomic) NSInteger flag;//当前系统标示（0：其他传值方式；1：block传值方式）

在A页面的试图控制器中

//RootViewController.m
1.- (IBAction)showSecondView:(id)sender {
2.SecondViewController *second = [[SecondViewController alloc] initWithNibName:@'SecondViewController' bundle:nil];
3.second.delegate = self;
4.second.flag = 0;
5.[self presentViewController:second animated:YES completion:nil];
6.}

情况2：A页面跳转到B页面，B页面再跳转回A页面主流方案：（1）通过委托delegate的方式实现
设置协议及方法

//SecondViewController.h
1.@protocol secondViewDelegate
2.-(void)showName:(NSString *)nameString;
3.@end

设置代理(为防止循环引用，此处采用了weak)


1.//SecondViewController.h
1.@interface SecondViewController : UIViewController
2.@property (nonatomic, weak)id<secondViewDelegate> delegate;
3.@property (nonatomic, copy) ablock block;
4.@end

调用

01.//SecondViewController.m
02.- (IBAction)delegateMethod:(id)sender {
03.if ([self notEmpty]) {
04.[self.delegate showName:self.nameTextField.text];
05.[self dismissViewControllerAnimated:YES completion:nil];
06.}else{
07.[self showAlert];
08.}
09.}

显示

.//RootViewController.m
2.-(void)showName:(NSString *)nameString{
3.self.nameLabel.text = nameString;
4.}

最重要也是最容易忽略的，就是一定要设置delegate的指向。（2）通过通知notification的方式实现
在B页面的控制器中，发送通知：

.//SecondViewController.m
02.- (IBAction)notificationMethod:(id)sender {
03.if ([self notEmpty]) {
04.[[NSNotificationCenter defaultCenter] postNotificationName:@'ChangeNameNotification' object:self userInfo:@{@'name':self.nameTextField.text}];
05.[self dismissViewControllerAnimated:YES completion:nil];
06.}else{
07.[self showAlert];
08.}
09.}

在A页面的控制器中，注册通知：

//RootViewController.m
2.- (void)viewDidLoad
3.{
4.[super viewDidLoad];
5.// Do any additional setup after loading the view from its nib.
6.[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(ChangeNameNotification:) name:@'ChangeNameNotification' object:nil];
7.}

当我们不使用时，要记得删掉通知：

.//RootViewController.m
2.-(void)dealloc{
3.[[NSNotificationCenter defaultCenter] removeObserver:self];
4.}

调用，显示

//RootViewController.m
2. 
3.-(void)ChangeNameNotification:(NSNotification*)notification{
4.NSDictionary *nameDictionary = [notification userInfo];
5.self.nameLabel.text = [nameDictionary objectForKey:@'name'];
6.}

（3）block方式实现分析：在B试图控制器中，定义一个block，参数为字符串

//SecondViewController.h
2.typedef void (^ablock)(NSString *str);
1.//SecondViewController.h
2. 
3.@property (nonatomic, copy) ablock block;

在B试图控制器中，当输入名字，点击对应的确定按钮后

01.- (IBAction)blockMethod:(id)sender {
02.if ([self notEmpty]) {
03.if (self.block) {
04.self.block(self.nameTextField.text);
05.[self dismissViewControllerAnimated:YES completion:nil];
06.}
07.}else{
08.[self showAlert];
09.}
10.}

在A试图显示，回调block

1.- (IBAction)showSecondWithBlock:(id)sender {
2.SecondViewController *second = [[SecondViewController alloc] initWithNibName:@'SecondViewController' bundle:nil];
3.[self presentViewController:second animated:YES completion:nil];
4.second.block = ^(NSString *str){
5.self.nameLabel.text = str;
6.};
7.}

在查阅资料的过程中，我还看到了以下几种方案：
（1）使用SharedApplication,定义一个变量来传递（感觉和单例的方式一样）
（2）使用文件，或者NSUserdefault来传递

01.//通过文件或者UserDefault方式存值(感觉不太适合此类传值，如果要用文件或者UserDefault方式存值的话，可以考虑此方式)
02.- (IBAction)userDefaultMethod:(id)sender {
03.if ([self notEmpty]) {
04.[[NSUserDefaults standardUserDefaults] setObject:self.nameTextField.text forKey:@'myNameText'];
05.[self dismissViewControllerAnimated:YES completion:nil];
06.}else{
07.[self showAlert];
08.}
09.}

在A试图控制器显示

01.-(void)viewDidAppear:(BOOL)animated{
02.[super viewDidAppear:animated];
03.//如果想测试通过UserDefault方式传值或者通过单例方式传值，取消以下注释即可
04./*
05.if ([[[NSUserDefaults standardUserDefaults] objectForKey:@'myNameText'] length] != 0) {
06.self.nameLabel.text = [[NSUserDefaults standardUserDefaults] objectForKey:@'myNameText'];
07.[[NSUserDefaults standardUserDefaults] setObject:@'' forKey:@'myNameText'];
08.}
09.DataSource *dataSource = [DataSource sharedDataSource];
10.if ([dataSource.myName length] != 0) {
11.self.nameLabel.text = dataSource.myName;
12.dataSource.myName = @'';
13.}
14.*/
15.}

B试图控制器

01.//通过单例方式传值(感觉不太适合此类传值，如果要用单例方式传值的话，可以考虑此方式)
02.- (IBAction)singletonMethod:(id)sender {
03.if ([self notEmpty]) {
04.DataSource *dataSource = [DataSource sharedDataSource];
05.dataSource.myName = self.nameTextField.text;
06.[self dismissViewControllerAnimated:YES completion:nil];
07.}else{
08.[self showAlert];
09.}
10.}

A试图控制器显示

01.-(void)viewDidAppear:(BOOL)animated{
02.[super viewDidAppear:animated];
03.//如果想测试通过UserDefault方式传值或者通过单例方式传值，取消以下注释即可
04./*
05.if ([[[NSUserDefaults standardUserDefaults] objectForKey:@'myNameText'] length] != 0) {
06.self.nameLabel.text = [[NSUserDefaults standardUserDefaults] objectForKey:@'myNameText'];
07.[[NSUserDefaults standardUserDefaults] setObject:@'' forKey:@'myNameText'];
08.}
09.DataSource *dataSource = [DataSource sharedDataSource];
10.if ([dataSource.myName length] != 0) {
11.self.nameLabel.text = dataSource.myName;
12.dataSource.myName = @'';
13.}
14.*/
15.}
16.@end

这里面用到了单例模式，编写了DataSource这个类，存放数据

1.//
02.//  DataSource.h
03.//  TestCallBack
04.//
05.//  Created by csdc-iMac on 14-7-17.
06.//  Copyright (c) 2014年 JuneWang. All rights reserved.
07.//
08. 
09.#import <Foundation/Foundation.h>
10. 
11.@interface DataSource : NSObject
12.@property (nonatomic, strong) NSString *myName;
13.+(DataSource*)sharedDataSource;
14.@end 
01.//
02.//  DataSource.m
03.//  TestCallBack
04.//
05.//  Created by csdc-iMac on 14-7-17.
06.//  Copyright (c) 2014年 JuneWang. All rights reserved.
07.//
08. 
09.#import 'DataSource.h'
10. 
11.@implementation DataSource
12.+(DataSource *)sharedDataSource{
13.static DataSource *dataSource = nil;
14.static dispatch_once_t once;
15.dispatch_once(&once, ^{
16.dataSource = [DataSource new];
17.});
18.return dataSource;
19.}
20.@end