Delegate 用于简单的页面传值方法

最新推荐文章于 2025-05-09 17:53:41 发布

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#Delegate #页面传值

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这篇博客详细介绍了如何在iOS应用中使用Delegate来实现页面间的简单传值。通过创建一个协议和代理方法，从页面B返回时将数据传递回页面A。文章通过实例代码展示了如何在页面A中声明和实现代理，以及在页面B中调用代理方法并将数据传回。

//有页面A和页面B

//页面A跳转到B

// 页面B 返回并传值给A

//A页面跳转B 不传值仅跳转

A页面代码

//.h

#import <UIKit/UIKit.h>

@interface ViewControllerA : UIViewController

@end

//.m

#import "ViewControllerA.h"

//把界面B的头文件引入

#import "ViewControllerB.h"

//添加代理

@interface ViewControllerA ()<ViewControllerBDelegate>

@property (nonatomic,strong) UILabel *labelShow;

@end

@implementation ViewControllerA

- (void)viewDidLoad {

[super viewDidLoad];

//创建Button

UIButton *button = [[UIButton alloc]initWithFrame:CGRectMake(100, 200, 100, 40)];

//设置button的名字

[button setTitle:@"跳转页面B" forState:UIControlStateNormal];

//设置Button的名字颜色

[button setTitleColor:[UIColor orangeColor] forState:UIControlStateNormal];

//设置button点击事件

[button addTarget:self action:@selector(btnPress) forControlEvents:UIControlEventTouchUpInside];

//将Button显示到页面上

[self.view addSubview:button];

//创建显示传过来值得label

UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 100, 40)];

//添加字体颜色

label.textColor = [UIColor redColor];

//添加属性

self.labelShow = label;

//添加到页面

[self.view addSubview:label];

}

//button点击触发的事件

-(void)btnPress

{

//创建实例

ViewControllerB *vcB = [[ViewControllerB alloc]init];

//页面跳转

[self presentViewController:vcB animated:YES completion:nil];

//声明代理人

vcB.Delegate = self;

}

//实现代理方法

-(void)addName:(NSString *)name

{

self.labelShow.text = name;

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

}

@end

页面B

//.h

#import <UIKit/UIKit.h>

//创建协议

@protocol ViewControllerBDelegate <NSObject>

@required

//协议方法即传值方法

-(void)addName:(NSString *)name;

@end

@interface ViewControllerB : UIViewController

//声明代理

@property (nonatomic,weak) id<ViewControllerBDelegate> Delegate;

@end

//.m

#import "ViewControllerB.h"

@interface ViewControllerB ()

//在扩展里面设置label属性

@property (nonatomic,strong) UILabel *labelName;

@end

@implementation ViewControllerB

- (void)viewDidLoad {

[super viewDidLoad];

//设置背景色

self.view.backgroundColor = [UIColor whiteColor];

//创建Label

UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 100, 40)];

//赋值

label.text = @"Clement";

//添加属性

self.labelName = label;

//在页面添加label控件

[self.view addSubview:label];

//创建button

UIButton *btn = [[UIButton alloc]initWithFrame:CGRectMake(100, 200, 100, 40)];

//设置标题

[btn setTitle:@"返回" forState:UIControlStateNormal];

//设置字体颜色

[btn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];

//添加事件

[btn addTarget:self action:@selector(btnPress) forControlEvents:UIControlEventTouchUpInside];

//页面添加button

[self.view addSubview:btn];

}

//buttond点击事件

-(void)btnPress

{

//调用代理并传值

[self.Delegate addName:self.labelName.text];

//消除本页面并返回

[self dismissViewControllerAnimated:YES completion:nil];

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

//此代码要把storyboard的ViewController 改成ViewControllerA 才能显示

//或者也可以在AppDelegate中写如下代码指定起始页面但是要删除设置里的启动文件Main

#import “ViewControllerA”

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

// Override point for customization after application launch.

self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];

self.window.backgroundColor = [UIColor whiteColor];

[self.window makeKeyAndVisible];

ViewControllerB *vcA = [[ViewControllerB alloc]init];

//指定根控制器

self.window.rootViewController = vcA;

return YES;

}

注意：点就是声明谁是代理人的时候页面切换在哪里就在哪里声明代理人

即button点击事件切换就要在button点击事件里进行声明Delegate

//沿线segue跳转则是在prepareForSegue 中进行声明

-(void)btnPress

{

//沿线跳转页面

[self performSegueWithIdentifier:@"popB" sender:nil];

}

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{

ViewControllerB *vcB = segue.destinationViewController;

vcB.Delegate = self;

}