objective-c 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;
}