objectivec 实现用户验证，登陆 Xcode iOS

- (void)viewDidLoad
{
    [super viewDidLoad];
 //加载窗口的时候把从文件里读出用户名。
 NSString *filePath = [self documentsPath:@"user.txt"]; 
    //读出文件存到数组username中
    NSArray *username = [NSArray arrayWithContentsOfFile:filePath];
    self.TXF1.text   = [username objectAtIndex:0];
    self.Txtpwd.text = [username objectAtIndex:1];
    //文本显示设为安全。星号
    self.Txtpwd.secureTextEntry = YES;
}

//登陆验证
- (IBAction)loginpage:(id)sender 
{
    NSLog(@"login...\n");
    NSString *filePath = [self documentsPath:@"user.txt"]; 
    //从user这个文件里读出用户名和密码是否与输入的相同
    NSArray *username = [NSArray arrayWithContentsOfFile:filePath];
    if([TXF1.text isEqualToString:[username objectAtIndex:0]] && [Txtpwd.text isEqualToString:[username objectAtIndex:1]])
    {
//如果验证正确，则重新打开一个窗口
        if(self.loginhome ==nil)
        {
            NSLog(@"loginhome");
            loginhome *homepage = [[loginhome alloc]initWithNibName:@"loginhome" bundle:nil];
            self.loginhome = [homepage autorelease];
            [self.view addSubview:self.loginhome.view];
        }
        else 
        {
            [self.view addSubview:self.loginhome.view];
        }

        NSLog(@"登陆成功！\n");
        
    }
    else 
    {
        NSLog(@"用户名或密码错误！\n");
        judgelogin = [[UIAlertView alloc]initWithTitle:@"提示" 
                                             message:@"用户名或密码错误！" 
                                            delegate:self 
                                   cancelButtonTitle:@"取消" 
                                   otherButtonTitles:@"确定",nil];
        [judgelogin show];
        [judgelogin release];
     
    }
    
}


//读程序目录而准备
-(NSString *)bundlePath:(NSString *)fileName {
    return [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:fileName];
}

-(NSString *)documentsPath:(NSString *)fileName {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    return [documentsDirectory stringByAppendingPathComponent:fileName];
}

-(NSString *)documentsPath {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    return documentsDirectory;
}