Obtain the device token as usual when the user opts in to receive remote push notifications. Then convert it to a base64 string that can be stored and used later.

Here’s how to do it. In your app delegate:

public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
	var tokenStringBase64 = deviceToken.GetBase64EncodedString(NSDataBase64EncodingOptions.None);
	//now you can store it for later use in local storage

To convert it back into an NSData object that you can send to third parties (like MixPanel and ExactTarget) that require the token as NSData:

var deviceToken = new NSData(tokenStringBase64, NSDataBase64DecodingOptions.None);