Firestore: create subcollection from iOS SDK

Question

Is it possible to create a subcollection within a document by using iOS SDK? I can't find any appropriate method on API and documentation doesn't provide any guides.

Answer 1

As a general rule, you don't explicitly "create" collections. Instead, you create documents and, if you've specified them as belonging to a collection that does not yet exist, then that collection will be created along the way.

So if you have a /users/jane document and want to add a history subcollection, you basically do this by creating the first document you want to appear in that subcollection -- i.e. something like:

Firestore.firestore().collection("users/jane/history").addDocument(historyData)

I believe this would work, too:

Firestore.firestore().document("users/jane/history/20171105")setData(historyData)