• 定义了宏

#define AccountKey @"account"
#define PwdKey @"pwd"
#define RmbPwdKey @"rmb_pwd"
#define AutoLoginKey @"auto_login"

• 定义属性

@property (weak, nonatomic) IBOutlet UITextField *accountField;
@property (weak, nonatomic) IBOutlet UITextField *pwdField;
@property (weak, nonatomic) IBOutlet UISwitch *rmbPwdSwitch;
@property (weak, nonatomic) IBOutlet UISwitch *autoLoginSwitch;

• 自动登录: 在viewDidLoad里读取上一次登录的信息

    - (void)viewDidLoad {  
        [super viewDidLoad];  
        // Do any additional setup after loading the view.  
          
        //读取上次的配置(记住密码、自动登录)  
        NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];  
        self.accountField.text = [defaults objectForKey:AccountKey];  
        self.rmbPwdSwitch.on = [[defaults objectForKey:RmbPwdKey] boolValue];  
        self.autoLoginSwitch.on = [[defaults objectForKey:AutoLoginKey] boolValue];  
        //处理密码  
        if (self.rmbPwdSwitch.isOn) {  
            self.pwdField.text = [defaults objectForKey:PwdKey];  
        }  
        //处理自动登录的情况  
        if (self.autoLoginSwitch.isOn) {  
            [self login]; // 点击了『登录』按钮  
        }  
    }  

• 点击记住密码按钮时存储用户信息

 -(IBAction)login {
    
    if (![self.accountField.text isEqualToString:@"admin"]) {
        //帐号不存在
        [MBProgressHUD showError:@"帐户不存在"];
        return;
    }
    if (![self.pwdField.text isEqualToString:@"123"]) {
        //帐号不存在
        [MBProgressHUD showError:@"密码错误"];
        return;
    }
    //显示一个蒙版
    [MBProgressHUD showMessage:@"正在登录中..."];
    
    //发送网络请求
    
    //隐藏蒙版
    [MBProgressHUD hideHUD];
    
    //验证成功，跳转到下一个控制器
    [self performSegueWithIdentifier:@"contacts" sender:self];
    
    //存储数据
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:self.accountField.text forKey:AccountKey];
    [defaults setObject:self.pwdField.text forKey:PwdKey];
    [defaults setObject:[NSNumber numberWithBool:self.rmbPwdSwitch.isOn] forKey:RmbPwdKey];
    [defaults setObject:[NSNumber numberWithBool:self.autoLoginSwitch.isOn]  forKey:AutoLoginKey];
    [defaults synchronize];
}