Xamarin 中的 UserDefault [英] UserDefault in Xamarin

问题描述

我正在尝试在 SettingViewController 关闭之前分配文本字段条目，并在 URLViewController 出现时检查它们.

I am trying to assign textfield entries just right before SettingViewController dismissed, and checking them while URLViewController appears.

但是，一旦我检查它返回 null，即使用户输入了所有必需的信息；

However, once I check it returns null even though user entered all required information;

//设置视图控制器

partial class SettingViewController : UIViewController
    {
        public ServerSettings sSettings;
        public SettingViewController (IntPtr handle) : base (handle)
        {
            this.Title = "Settings";
            this.sSettings = new ServerSettings();

        }

        public override void ViewWillDisappear (bool animated)
        {
            sSettings.server=serverTF.Text;
            sSettings.port = portTF.Text;
            sSettings.password = passwordTF.Text;
            sSettings.userid = inboxuserTF.Text;
            sSettings.username = usernameTF.Text;
        }
    }

//URLViewController

//URLViewController

public override void ViewWillAppear(bool animated)
        {
        base.ViewWillAppear (animated);
        SettingViewController callSetting = this.Storyboard.InstantiateViewController ("SettingViewController") as SettingViewController;

        if (callSetting == null)
            throw new Exception("callSetting is null"); // Or if you can handle having a null callSetting then correct for it, but realistically this is a problem, so I'd throw an Exception

        if (callSetting.sSettings == null)
            throw new Exception("sSetting is null"); // Or if you can handle having a null callSetting.sSetting then correct it (such as using a default value).

        if (string.IsNullOrEmpty(callSetting.sSettings.password)==true) 
            Console.WriteLine("is null or empty");
        else 
            Console.WriteLine (callSetting.sSettings.password);

    }

即使用户填写了所有文本字段条目，它也会返回 null.//设置视图控制器

Even though user fullfill all the textfield entries, it returns null. //SettingsViewController

//URLViewController

//URLViewController

推荐答案

我会通过使用 dictionary& 来解决这个问题用户默认设置如下:

I would approach the problem by using dictionary& userdefaults as follows:

在 B 视图控制器中，将用户条目保留在字典中，将其映射并分配给用户默认值.

In the B Viewcontroller, keep the user entries in the dictionary, map it and assign it to the userdefault.

partial class BViewController : UIViewController
{
    const string server = "server";
    const string port = "port";
    const string password = "password";
    const string username = "username";
    const string inboxuserid = "inboxuserid";
    .............
    .............



  public override void ViewWillDisappear (bool animated)
  {
    var appDefaults = new NSDictionary (server, serverTF.Text, port, portTF.Text, password, passwordTF.Text,username,usernameTF.Text, inboxuserid,inboxuserTF.Text);
    NSUserDefaults.StandardUserDefaults.RegisterDefaults (appDefaults);
    NSUserDefaults.StandardUserDefaults.Synchronize ();
  }

}

并在 A ViewController 中检索它们，如下所示:

and retrieve them in the A ViewController as follows:

partial class AViewController : UIViewController
 {



  public override void ViewWillAppear(bool animated)
   {
    NSUserDefaults.StandardUserDefaults.RegisterDefaults (appDefaults);
    NSUserDefaults.StandardUserDefaults.Synchronize ();
    var username = NSUserDefaults.StandardUserDefaults.StringForKey ("username");
    Console.WriteLine (username);
    }
}

以下链接中也有很好的例子:

There are also good examples in the following links:

https://github.com/xamarin/monotouch-样本/blob/master/AppPrefs/Settings.cshttp://forums.xamarin.com/discussion/9089/nsuserdefaults-standarduserdefaults-returns-null-first-time

这篇关于Xamarin 中的 UserDefault的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！