iOS中多视图的传值 属性传值和代理传值

首先创建两个类 ，FirstViewController和SecondViewController，都继承于UIViewController

#import "AppDelegate.h"
#import "FirstViewController.h"

@interface AppDelegate ()

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    //初始化视图控制器
    FirstViewController *firstVc=[[FirstViewController alloc]init];
    //设置根视图控制器
    self.window.rootViewController=firstVc;
    return YES;
}

#import <UIKit/UIKit.h>
#import "SecondViewController.h"
@interface FirstViewController : UIViewController<UITextFieldDelegate,posVlueDelegate>
@property(strong,nonatomic) UITextField *textName;
@end

#import "FirstViewController.h"

@interface FirstViewController ()

@end

@implementation FirstViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //设置背景视图的颜色
    self.view.backgroundColor=[UIColor redColor];
    //初始化
    self.textName=[[UITextField alloc] initWithFrame:CGRectMake(100, 150, 200, 40)];
    //设置文本框的颜色
    self.textName.backgroundColor=[UIColor whiteColor];
    self.textName.borderStyle=1;
    [self.view addSubview:self.textName];
    
}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    SecondViewController *secondVc=[[SecondViewController alloc] init];
    //设置属性值 即 传值给SecondViewController
    secondVc.str=self.textName.text;
    //进入第二页
    [self presentViewController:secondVc animated:YES completion:^{
        NSLog(@"FirstViewController切换到SecondViewController");
    }];
    //指定代理
    secondVc.delegate=self;
}
//实现协议方法
-(void)posVlue:(NSString *)str
{
    self.textName.text=str;
}







- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#import <UIKit/UIKit.h>
//创建协议
@protocol posVlueDelegate<NSObject>
-(void)posVlue:(NSString *)str;//协议方法

@end

@interface SecondViewController : UIViewController
@property(strong,nonatomic)UITextField *textName;
@property(strong,nonatomic)NSString *str;
//创建协议类型的属性
@property(assign,nonatomic)id<posVlueDelegate>delegate;
@end

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor=[UIColor grayColor];
    self.textName=[[UITextField alloc] initWithFrame:CGRectMake(100, 150, 200, 50)];
    self.textName.backgroundColor=[UIColor whiteColor];
    self.textName.borderStyle=1;
    [self.view addSubview:self.textName];
    //接受FirstViewController传过来的值
    self.textName.text=self.str;
}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    [self dismissViewControllerAnimated:YES completion:^{
        NSLog(@"SecondViewController切换到FirstViewController");
    }];
    
    if (self.delegate) {
        [self.delegate posVlue:self.textName.text];
    }
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

总结：

1.页面之间传值方式

       属性传值

       适用于 正向传值

     1.1 在要显示信息的页面创建属性

     1.2 在要传值的页面 设置属性值

     1.3 在显示页面的viewDidLoad方法中，接受属性值

代理传值

 适用于反向传值

 1.创建协议及协议方法，在反向传值的页面SecondViewController中

 2.创建协议类型的属性，在SecondViewController中创建属性

    @property(assign,nonatomic) id<posVlueDelegate> delegate;

 3.调用属性即 delegate

    SecondViewController页面中 对象传值的方法中调用

 if (self.delegate) {

 [self.delegate posVlue:self.textName.text];

 }

 4.在第一页 即显示修改富哦信息的页面

 遵循协议 实现协议方法 指定代理对象（即 在页面传递参数的方法中为代理赋值-(void)posVlue:(NSString *)str

 {

 self.textField.text=str;

 }）