ios 得用代理反向傳值

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   應用情境：有時時候從介面A跳轉到介面B,介面B在返回的時候需要將處理的結果傳遞給A.

   實現思路：1，定義一個負責傳值的協義，介面A擁有該協義屬性，並實現該協義中的方法

                       2，介面B也擁有該協義屬性（代理要求兩者都具有相同對象的引用 ），然後在返回的時候擷取介面A的引用指標，並且指定B中協義的調用目標為A,調用協義中的傳值方法.

 具體代碼:

    A的標頭檔 ：

#import <UIKit/UIKit.h>

@protocol passValueDelegate <NSObject>

-(void) setValue:(NSString *)param;

@end

@interface ViewController :UIViewController

@propertyid<passValueDelegate> passValueDelegate;

@end

  A的實現檔案 :
 

#import "ViewController.h"

#import "ViewController2.h"

@interfaceViewController ()

{

}

@end

@implementation ViewController

- (void)viewDidLoad

{

    [superviewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

    UIButton *btn =[UIButtonbuttonWithType:UIButtonTypeRoundedRect];

    btn.frame=CGRectMake(100,100, 200,40);

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

    [btn addTarget:selfaction:@selector(btn)forControlEvents:UIControlEventTouchUpInside];

    [self.viewaddSubview:btn];

    

    self.view.backgroundColor=[UIColorredColor];

}

-(void) setValue:(NSString *)param{

    NSLog(@"pass value is:%@",param);

}

-(void)btn

{

    [self.navigationController pushViewController:[[ViewController2 alloc]init] animated:YES];

}

- (void)didReceiveMemoryWarning

{

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end

B的標頭檔 ：
 

#import <UIKit/UIKit.h>

@interface ViewController2 :UIViewController

@end

B的實現檔案:

#import "ViewController2.h"

#import "ViewController.h"

@interfaceViewController2 ()

@propertyid<passValueDelegate> passValueDelegate;

@end

@implementation ViewController2

- (void)viewDidLoad

{

    [superviewDidLoad];

    UIButton *btn =[UIButtonbuttonWithType:UIButtonTypeRoundedRect];

    btn.frame=CGRectMake(100,100, 200,40);

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

    [btn addTarget:selfaction:@selector(btn)forControlEvents:UIControlEventTouchUpInside];

    [self.viewaddSubview:btn];

}

-(void)btn

{

  //  NSLog(@"%@",self.navigationController.childViewControllers[0]);

    self.passValueDelegate=self.navigationController.childViewControllers[0];

    [self.navigationControllerpopToRootViewControllerAnimated:YES];

   

    [self.passValueDelegatesetValue:@"123456789"];

}

- (void)didReceiveMemoryWarning

{

    [superdidReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end