UI基础-实现页面跳转和输入值的传递

完成下面输入值传递的功能: 创建一个根视图控制器，加载在window上。并且添加一个lable标签和button按钮。单击button时，弹出一个模态视图。模态视图中包含一个返回按钮和textField输入框。修改textField的值并点击返回按钮返回到根视图时，将textField的值显示到label标签上。

下面用代理实现:

首先要清楚谁需要委托，Modal想要去修改label的值，但是他自己做不了这件事情，所以Modal需要找一个具备这样能力的一个委托人。

先来创建根视图控制器和模态视图控制器并设置label、button、textField:

RootViewController:

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //背景颜色
    self.view.backgroundColor = [UIColor grayColor];
    
    //设置Label
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(100, 100, 150, 50)];
    label.tag = 101;
    label.textAlignment = NSTextAlignmentCenter;
    label.backgroundColor = [UIColor orangeColor];
    [self.view addSubview:[label autorelease]];
    
    //设置Button
    UIButton *goButton = [UIButton buttonWithType:UIButtonTypeCustom];
    goButton.frame = CGRectMake(100, 200, 150, 50);
    goButton.backgroundColor = [UIColor orangeColor];
    [goButton setTitle:@"跳转" forState:UIControlStateNormal];
    [goButton addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:goButton];
}

- (void)btnClick:(UIButton *)btn
{
    ModalViewController *modalVC = [[ModalViewController alloc] init];
    //弹出模态视图
    [self presentViewController:modalVC animated:YES completion:nil];
    [modalVC release];
}

ModalViewController:

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //背景颜色
    self.view.backgroundColor = [UIColor orangeColor];
    
    //设置TextField
    UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(100, 100, 150, 50)];
    textField.tag = 101;
    textField.placeholder = @"请输入内容";
    textField.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:[textField autorelease]];
    
    //设置Button
    UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
    backButton.frame = CGRectMake(100, 200, 150, 50);
    backButton.backgroundColor = [UIColor grayColor];
    [backButton setTitle:@"返回" forState:UIControlStateNormal];
    [backButton addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:backButton];
}

-(void) btnClick: (UIButton *) btn
{
    //关闭模态视图
    [self dismissViewControllerAnimated:YES completion:nil];
}

AppDelegate：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    self.window = [[[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds] autorelease];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    
    RootViewController *rootVC = [[RootViewController alloc] init];
    self.window.rootViewController = [rootVC autorelease];
    
    return YES;
}

基本框架已经完成，开始设置代理模式

Modal要去传一个值修改label，自己不能做，找个代理人，并且代理人应该具备修改label的这样一个功能

在Modal中添加协议和代理人:

@protocol ModalViewControllerDelegate <NSObject>

-(void) changeLabelText: (NSString *) text;

@end

@interface ModalViewController : UIViewController

@property (nonatomic, assign) id<ModalViewControllerDelegate> delegate; //设置代理人

@end

并在自己的实现文件中让代理去做这件事情:

点击返回时设置

-(void) btnClick: (UIButton *) btn
{
    //获取textFiled
    UITextField *textField = (UITextField *) [self.view viewWithTag:101];
    
    //安全判断
    if ( [self.delegate respondsToSelector:@selector(changeLabelText:)] ) {
        //代理去更改labelText
        [self.delegate changeLabelText:textField.text];
    }
    
    //关闭模态视图
    [self dismissViewControllerAnimated:YES completion:nil];
}

Root要做代理人就要遵守协议:

@interface RootViewController : UIViewController <ModalViewControllerDelegate>

@end

遵守了协议当然要实现:

//实现协议的方法,功能是将text的内容显示到label上来
-(void) changeLabelText: (NSString *) text;
{
    UILabel *label = (UILabel *)[self.view viewWithTag:101];
    label.text = text;
}

并且在点击跳转按钮时设置自己为Modal的代理:

- (void)btnClick:(UIButton *)btn
{
    ModalViewController *modalVC = [[ModalViewController alloc] init];
    modalVC.delegate = self; //设置代理
    
    //弹出模态视图
    [self presentViewController:modalVC animated:YES completion:nil];
    [modalVC release];
}

ok,大功告成，试试效果:

点击跳转，并在弹出界面输入框中输入文字:

输入完成后点击返回，返回到根视图界面，界面的label已经被设置上了值:

代码资源: http://download.youkuaiyun.com/detail/shawn_chang/8431467