delegate 传值demo

代理的一般使用场合为：

1.对象B的内部发生一些事，想通知A,比如B通知A改颜色；

2.对象A想监听对象B内部发生了什么事情；

3.对象B想在自己的方法内部调用对象A的某个方法，并且对象B不能对对象A有耦合依赖；（A遵守协议，执行代理方法）

4.对象B想传递数据给对象A;

……………………

以上情况，结果都一样：对象A是对象B的代理（delegete），即B.delegate = A，对象B让对象A作为它的代理，帮它去做事；

 

一个最简单的列子来说明delegate的简单使用：界面A push 界面B,然后界面B pop 界面A的时候改变界面A的颜色，即界面B返回传值给界面A;

界面A为 AViewController,界面B为 BViewController

 

AViewController.h

1 #import <UIKit/UIKit.h>
2 #import "BViewController.h"
3 
4 @interface AViewController : UIViewController<ChangeColorDelegate>
5 {
6     BViewController *B;
7 }
8 @end

AViewController.m

 1 - (void)viewDidLoad
 2 {
 3    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
 4     button.frame = CGRectMake(140, 100, 60, 30);
 5     button.backgroundColor = [UIColor whiteColor];
 6     [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
 7     button.layer.cornerRadius = 8.0;
 8     [button setTitle:@"推出B" forState:UIControlStateNormal];
 9     [button addTarget:self
10                action:@selector(buttonClick:)
11     forControlEvents:UIControlEventTouchUpInside];
12     [self.view addSubview:button];
13     
14     B = [[BViewController alloc] init];
15     B.delegate = self;//遵守协议
16 }
17 
18 - (void)buttonClick:(id)sender
19 {
20     [self.navigationController pushViewController:B animated:YES];
21 }
22 //协议方法
23 - (void)changeViewBackGroundColor:(UIColor *)color
24 {
25     self.view.backgroundColor = color;
26 }

 

BViewController.h

1 #import <UIKit/UIKit.h>

2 @protocol ChangeColorDelegate <NSObject>
3 - (void)changeViewBackGroundColor:(UIColor *)color;//协议方法
4 @end

5 @interface BViewController : UIViewController
6 @property (nonatomic,retain)id<ChangeColorDelegate>delegate;
7 @end

BViewController.m

 1 - (void)viewDidLoad
 2 {
 3     [super viewDidLoad];
 4     self.view.backgroundColor = [UIColor redColor];
 5     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
 6     button.frame = CGRectMake(140, 100, 60, 30);
 7     button.backgroundColor = [UIColor whiteColor];
 8     button.layer.cornerRadius = 8.0;
 9     [button setTitle:@"变色" forState:UIControlStateNormal];
10     [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
11     [button addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
12     [self.view addSubview:button];
13 }
14 - (void)buttonClick:(id)sender
15 { 
16 //    if ([self.delegate respondsToSelector:@selector(changeViewBackGroundColor:)]) {
17 //        [self.delegate changeViewBackGroundColor:[UIColor colorWithRed:arc4random()%255/255.0f green:arc4random()%255/255.0f blue:arc4random()%255/255.0f alpha:1]];
18 //    }
19     //这样写和上面的是一个意思，不需要加判断更直接，但有时候还是需要加判断的
20     [self.delegate changeViewBackGroundColor:[UIColor colorWithRed:arc4random()%255/255.0f green:arc4random()%255/255.0f blue:arc4random()%255/255.0f alpha:1]];
21     [self.navigationController popViewControllerAnimated:YES];
22 }

这样就实现了简单的代理传值

posted @ 2015-01-08 17:36  莫等闲，白了少年头  阅读(227)  评论(0)  编辑  收藏  举报