代理传值 回调的使用

我以前曾今写过一篇博客，是讲解代理传值的，讲解的很不好，有许多没有讲清楚的地方，现在抽个时间将它讲解清楚，代理delegate 使用他进行传值，其实他就类似于一个第三方授权一样，我要从A这个类中取出a这个值，我可以使用代理，让代理去执行取值

我这边写了两个类一个teacher类，一个student类，我这边为了更加明朗的显示出来，所以我将这两个类写成视图的格式，这样就能更直观的现实出来；类似于两个页面的传值；回调其实，回调和代理都可以实现两个页面的传值

我在teacher，中加入了一个按钮，和一个文本框，用来接受student页面传输过来的值；使用代理的时候一定要将代理传输过去，传递代理

代码如下，这个是teacher类的：

//

//  teacherViewController.h

//  dreamDemo

//

//  Created by apple on 14-11-18.

//  Copyright (c) 2014年 apple. All rights reserved.

//

#import <UIKit/UIKit.h>

typedef void(^myBlock) (NSString *);

@protocol myDelegate <NSObject>

-(void)myBlick:(myBlock)block;

-(void)setText1:text;

@end

@interface teacherViewController : UIViewController<myDelegate>

@property(strong,nonatomic)UIButton *button;

@property(strong,nonatomic)UITextField *label;

@end

-------------------------------------------------------------------------------------

//

//  teacherViewController.m

//  dreamDemo

//

//  Created by apple on 14-11-18.

//  Copyright (c) 2014年 apple. All rights reserved.

//

#import "teacherViewController.h"

#import "studentViewController.h"

@interface teacherViewController ()

@end

@implementation teacherViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view from its nib.

    [self initView];

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

-(void)initView{

    self.button=[UIButton buttonWithType:UIButtonTypeCustom];

    self.button.backgroundColor=[UIColor blackColor];

    self.button.frame=CGRectMake(50, 100, 120, 100);

    [self.button setTitle:@"push" forState:UIControlStateNormal];

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

    [self.view addSubview:self.button];

    self.label=[[UITextField alloc]initWithFrame:CGRectMake(50, 230, 200, 100)];

    self.label.backgroundColor=[UIColor redColor];

    [self.view addSubview:self.label];

}

-(void)chuan{

    studentViewController *viewController=[[studentViewController alloc]initWithNibName:nil bundle:nil];

    viewController.delegate=self;

    [self.navigationController pushViewController:viewController animated:YES];

}

-(void)setText1:text{

    _label.text=text;

}

-(void)myBlick:(myBlock)block{

    block(_label.text);

}

@end

-------------------------------------------------------------------------------------

这里是student类的

//

//  studentViewController.h

//  dreamDemo

//

//  Created by apple on 14-11-18.

//  Copyright (c) 2014年 apple. All rights reserved.

//

#import <UIKit/UIKit.h>

#import "teacherViewController.h"

@interface studentViewController : UIViewController

@property  id<myDelegate> delegate;

@property(strong,nonatomic)UIButton *button;

@property(strong,nonatomic)UITextField *label;

@property(strong,nonatomic)UILabel *huimie;

@end

//

//  studentViewController.m

//  dreamDemo

//

//  Created by apple on 14-11-18.

//  Copyright (c) 2014年 apple. All rights reserved.

//

#import "studentViewController.h"

#import "teacherViewController.h"

@interface studentViewController ()

@end

@implementation studentViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view from its nib.

        [self initView];

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

-(void)initView{

    self.button=[UIButton buttonWithType:UIButtonTypeCustom];

    self.button.backgroundColor=[UIColor redColor];

    self.button.frame=CGRectMake(50, 100, 120, 100);

    [self.button setTitle:@"返回" forState:UIControlStateNormal];

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

    [self.view addSubview:self.button];

    

    self.label=[[UITextField alloc]initWithFrame:CGRectMake(50, 230, 200, 100)];

    self.label.backgroundColor=[UIColor yellowColor];

    [self.view addSubview:self.label];

    self.huimie=[[UILabel alloc]initWithFrame:CGRectMake(10, 10, 100, 30)];

    self.huimie.backgroundColor=[UIColor yellowColor];

    [self.view addSubview:self.huimie];

}

-(void)fanhui{    

    [_delegate setText1:_label.text];

    [_delegate myBlick:^(NSString *string) {

        _huimie.text=string;

    }];

    

    [self.navigationController popViewControllerAnimated:YES];

}

@end

上面就是我实现这个demo的代码，代码中现实通过代理去向teacher类中传递值，然后再通过回调将刚刚传给teacher传递的值，再次回调过来，将这个回调过来的值给另一个label使用。end