Hey!
Yesterday I completed the saving system implementation, and I went to the JSON tutos when I saw the IDictionary that maps the JObject.
Why IDictionary instead of the ordinary Dictionary?
I never saw IDictionary before 
The IDictionary is an interface which gives us certain mapping features when working with structures like a JObject.
It’s actually going to go away in the next version of the tutorial, as it turns out the functions we need most from the JObject (mainly Add, [], and iterating over the KeyValuePairs) are already featured in the JObject.
The same with JArrays. You can manipulate these directly without mapping them to an IList.
For example: This is the code used for a QuestStatus from the Tutorial:
public QuestStatus(JToken objectState)
{
if (objectState is JObject state)
{
IDictionary<string, JToken> stateDict = state;
quest = Quest.GetByName(stateDict["questName"].ToObject<string>());
completedObjectives.Clear();
if (stateDict["completedObjectives"] is JArray completedState)
{
IList<JToken> completedStateArray = completedState;
foreach (JToken objective in completedStateArray)
{
completedObjectives.Add(objective.ToObject<string>());
}
}
}
}
public JToken CaptureAsJToken()
{
JObject state = new JObject();
IDictionary<string, JToken> stateDict = state;
stateDict["questName"] = quest.name;
JArray completedState = new JArray();
IList<JToken> completedStateArray = completedState;
foreach (string objective in completedObjectives)
{
completedStateArray.Add(JToken.FromObject(objective));
}
stateDict["completedObjectives"] = completedState;
return state;
}
But it can be replaced with:
public QuestStatus(JToken objectState)
{
if (objectState is JObject stateDict)
{
quest = Quest.GetByName(stateDict["questName"].ToObject<string>());
completedObjectives.Clear();
if (stateDict["completedObjectives"] is JArray completedStateArray)
{
foreach (JToken objective in completedStateArray)
{
completedObjectives.Add(objective.ToObject<string>());
}
}
}
}
public JToken CaptureAsJToken()
{
JObject stateDict = new JObject();
stateDict["questName"] = quest.name;
JArray completedStateArray = new JArray();
foreach (string objective in completedObjectives)
{
completedStateArray.Add(JToken.FromObject(objective));
}
stateDict["completedObjectives"] = completedState;
return state;
}