//把用户名和密码存储到便好设置
NSUserDefaults *userDefault=[NSUserDefaults standardUserDefaults];
[userDefault setObject:self.userTextfield.text forKey:@"userName"];
[userDefault setObject:self.passwordTextField.text forKey:@"password"];
//只有调用同步方法,才会真正写入文件
[userDefault synchronize];