To save the "MyFun item" data, it is recommended to serialize the data and save it to a json file or an xml file.
For JSON serialization, you can install the Nuget package Newtonsoft.Json
. For more info, you can refer to this document.
Or XML serialization, you can create an instance of XmlSerializer Class to serializes and deserializes objects into and from XML document.
Here are some related SO threads you can refer to.
How to write a JSON file in C#?
Serialize an object to XML
If you have got the serialized data, as mentioned in the comment, you can download official demo Xamarin.iOS - Introduction to iCloud, then pass it to MonkeyDocument.DocumentString
.