#import <UIKit/UIKit.h>

@interface FirstViewController : UIViewController

@end

#import "FirstViewController.h"
#import "SecondViewController.h"

@interface FirstViewController ()<SecondViewControllerDelegate>

/** 用于寫入數(shù)據(jù)，最后該數(shù)據(jù)用于傳遞給第二個界面 */
@property (weak, nonatomic) IBOutlet UITextField *first2Second;
/** 用于顯示第二個界面返回來時傳遞的數(shù)據(jù) */
@property (weak, nonatomic) IBOutlet UITextField *displayWithSecond;

@end

@implementation FirstViewController

- (void)viewDidLoad {
  [super viewDidLoad];

}

#pragma mark - Navigation

//點擊傳遞按鈕時會自動調(diào)用此方法
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
  SecondViewController *vc = (SecondViewController *)segue.destinationViewController;
  if (self.first2Second.text.length > 0) {
    //將該界面中的數(shù)據(jù)傳遞給第二個界面
    vc.name = self.first2Second.text;
  }

  //設(shè)置當(dāng)前控制器為SecondViewController控制器的代理
  vc.delegate = self;
}

#pragma mark - 實現(xiàn)SecondViewControllerDelegate中的協(xié)議方法
-(void)secondViewControllerDidDit:(SecondViewController *)viewController andName:(NSString *)name
{
  //將第二個界面中的數(shù)據(jù)返回給第一個界面（此界面）
  self.displayWithSecond.text = name;
}

@end

#import <UIKit/UIKit.h>
@class SecondViewController;

@protocol SecondViewControllerDelegate <NSObject>

/** SecondViewControllerDelegate協(xié)議中的方法 */
-(void)secondViewControllerDidDit:(SecondViewController *)viewController andName:(NSString *)name;

@end

@interface SecondViewController : UIViewController

@property(nonatomic,strong) NSString *name;
@property(nonatomic,weak) id<SecondViewControllerDelegate> delegate;

@end

#import "SecondViewController.h"

@interface SecondViewController ()
/** 用于寫入數(shù)據(jù)，最后將數(shù)據(jù)返回給第一個界面 */
@property (weak, nonatomic) IBOutlet UITextField *second2First;
/** 用于顯示第一個界面?zhèn)鬟^來的數(shù)據(jù) */
@property (weak, nonatomic) IBOutlet UITextField *displayWithFirst;
/** 點擊此按鈕，第二個控制器將彈出棧，界面將返回到第一個界面 */
- (IBAction)second2First:(UIButton *)sender;

@end

@implementation SecondViewController

- (void)viewDidLoad {
  [super viewDidLoad];

  //顯示第一個界面?zhèn)鬟f過來的數(shù)據(jù)信息
  self.displayWithFirst.text = self.name;

}

//點擊該按鈕，數(shù)據(jù)將返回給第一個界面顯示
- (IBAction)second2First:(UIButton *)sender {
  if (self.second2First.text.length > 0) {
    //如果有實現(xiàn)該協(xié)議方法的控制器，則將數(shù)據(jù)傳給該控制器
    if ([self.delegate respondsToSelector:@selector(secondViewControllerDidDit:andName:)]) {
      [self.delegate secondViewControllerDidDit:self andName:self.second2First.text];
    }
  }
  [self.navigationController popViewControllerAnimated:YES];
}

@end