代理传值

代理(delegate)传值 ---- 顾名思义就是委托别人办事，就是当一件事情发生后，自己不处理，让别人来处理。//代理传值
注意:从后往前传(如果从前往后传,会传不成功)
//流程:
1.后一个界面定义一个协议,并且定义一个属性叫delegate
2.在前一个界面进入后一个界面的瞬间,(即:创建完成一个界面之后),让前一个界面作为后一个界面的delegate
3.前一个界面实现代理方法
4.后一个界面在合适的机会, 让代理, 执行,代理方法 (传的值以参数的形式 含在代理方法里)
代码如下:
[objc] view plaincopy




#import "FirstViewController.h"

#import "SecondViewController.h"

#import "UIButton+Create.h"

@interface FirstViewController ()

{

UILabel * _label;

}

@end

@implementation FirstViewController

- (void)dealloc

{

[_label release];

[super dealloc];

}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

{

self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

if (self) {

// Custom initialization

}

return self;

}

- (void)viewDidLoad

{

[super viewDidLoad];

self.view.backgroundColor = [UIColor redColor];

self.navigationItem.title = @"首页";

self.view.userInteractionEnabled = YES;

/**

* 1.创建一个UIButton,

* 2.并添加响应事件,从首页跳转到第二个页面.

*/

UIButton * button = [UIButton systemButtonWithFrame:CGRectMake(100, 120, 50, 50) title:@"Push" target:self action:@selector(didClickButtonAction)];

button.userInteractionEnabled = YES;

[self.view addSubview:button];

/**

* 1.在第1个界面创建一个UILabel

* 2.把第二页输入框输入的字符串,通过代理方法传过来

* 3.然后通过赋值给UILabel

*/

_label = [[UILabel alloc]initWithFrame:CGRectMake(50, 80, 200, 30)];

_label.backgroundColor = [UIColor greenColor];

[self.view addSubview:_label];

// Do any additional setup after loading the view.

}

- (void)didClickButtonAction

{

/**

* 1.用push的方法推出下一个页面

* 2.把第二页输入框输入的字符串,通过代理方法传过来

* 3.从而实现把首页输入框输入的字符串,传到第二页的UILabel上.

*/

SecondViewController * secondVC = [[SecondViewController alloc]init];

secondVC.delegate = self;//确认代理

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

[secondVC release];

}

//实现代理方法

- (void)passByValueSecondVC:(SecondViewController *)secondVC text:(NSString *)text

{

_label.text = text;

}

- (void)didReceiveMemoryWarning

{

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

[objc] view plaincopy




#import <UIKit/UIKit.h>

@class SecondViewController;

@protocol secondViewControllerDelegate <NSObject>

- (void)passByValueSecondVC:(SecondViewController *)secondVC text:(NSString *)text;

@end

@interface SecondViewController : UIViewController

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

@end

[objc] view plaincopy




#import "SecondViewController.h"

#import "UIButton+Create.h"

#import "FirstViewController.h"

@interface SecondViewController ()

{

UITextField * _textField;//创建一个输入框

}

@end

@implementation SecondViewController

- (void)dealloc

{

[_textField release];

[super dealloc];

}

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

{

self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

if (self) {

// Custom initialization

}

return self;

}

- (void)viewDidLoad

{

[super viewDidLoad];

self.view.backgroundColor = [UIColor orangeColor];

self.navigationItem.title = @"第二页";

/**

* 1.创建一个UIButton,

* 2.并添加响应事件,从第二个页面返回到首页.

*/

UIButton * button = [UIButton systemButtonWithFrame:CGRectMake(100, 120, 50, 50) title:@"Back" target:self action:@selector(didClickButtonAction)];

[self.view addSubview:button];

/**

* 1.在第二个界面创建一个输入框

*

*/

_textField = [[UITextField alloc]initWithFrame:CGRectMake(50, 80, 200, 30)];

_textField.borderStyle = UITextBorderStyleRoundedRect;

[self.view addSubview:_textField];

// Do any additional setup after loading the view.

}

- (void)didClickButtonAction

{

//调用代理方法,_textField.text传值

[_delegate passByValueSecondVC:self text:_textField.text];

[self.navigationController popToRootViewControllerAnimated:YES];

}

- (void)didReceiveMemoryWarning

{

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end