界面的跳转和传值

//在APPDelegate.h中，即项目的入口部分
//didFinishLaunchingWithOptions该方法表示APP启动完毕，接下来进入自定义界面
//如下MyViewController是自定义的类，即一个界面实现UIViewController接口

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.

self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

self.window.backgroundColor = [UIColor whiteColor];

MyViewController *myController = [[MyViewController alloc] init];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:myController];

self.window.rootViewController = navController;
[self.window makeKeyAndVisible];

return YES;
}

//MyViewController.h
//定义四个控件
@interface MyViewController : UIViewController

@property (strong, nonatomic) UILabel *labelNum;
@property (strong, nonatomic) UILabel *labelPwd;

@property (strong, nonatomic) UITextField *fieldNum;
@property (strong, nonatomic) UITextField *fieldPwd;

@end

//MyViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.

self.labelNum = [[UILabel alloc] init];
self.labelNum.frame = CGRectMake(100, 100, 50, 20);
self.labelNum.text = @"Num: ";

self.fieldNum = [[UITextField alloc] init];
self.fieldNum.frame = CGRectMake(150, 100, 100, 20);
self.fieldNum.borderStyle = UITextBorderStyleRoundedRect;

self.labelPwd = [[UILabel alloc] init];
self.labelPwd.frame = CGRectMake(100, 150, 50, 20);
self.labelPwd.text = @"Pwd: ";

self.fieldPwd = [[UITextField alloc] init];
self.fieldPwd.frame = CGRectMake(150, 150, 100, 20);
self.fieldPwd.borderStyle = UITextBorderStyleRoundedRect;

UIButton *btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
btn.frame = CGRectMake(100, 200, 80, 20);
btn.backgroundColor = [UIColor grayColor];
[btn setTitle:@"login" forState:UIControlStateNormal];

//设置按钮监听事件，监听方法为login
[btn addTarget:self action:@selector(login) forControlEvents:UIControlEventTouchDown];

[self.view addSubview:self.labelNum];
[self.view addSubview:self.fieldNum];

[self.view addSubview:self.labelPwd];
[self.view addSubview:self.fieldPwd];

[self.view addSubview:btn];
}

//页面跳转，并传递参数

-(void) login{
NSLog(@"login");

NSString *num = self.fieldNum.text;
NSString *pwd = self.fieldPwd.text;

if([num isEqualToString:@"123"] == TRUE){

NSLog(@"yes");

//初始化要跳转的界面
MainViewController *mm = [[MainViewController alloc] init];

//把账号密码传递到下个界面
[mm initData:num two:pwd];

//开始跳转
[self.navigationController pushViewController:mm animated:FALSE];
}else{
NSLog(@"error");
}

}

//MainViewController.h

@interface MainViewController : UIViewController
//@property( nonatomic) NSString

//传递两个参数a、b NSString 类型
-(void) initData:(NSString *) a two:(NSString *) b;

@end

//接收参数，并保存
-(void) initData:(NSString *) a two:(NSString *) b{
self.num = a;
self.pwd = b;

NSLog(@"%@,%@", self.num, self.pwd);
}

//效果图