Warnings of depreciated methods in MultiPeer.swift file

[thoughtcastapp]

Getting these alert warnings when I compile, thought they might want to be addressed/updated:

Line 159:
'archivedData(withRootObject:)' was deprecated in iOS 12.0: Use +archivedDataWithRootObject:requiringSecureCoding:error: instead

line 174:
'archivedData(withRootObject:)' was deprecated in iOS 12.0: Use +archivedDataWithRootObject:requiringSecureCoding:error: instead

line 297:
'unarchiveObject(with:)' was deprecated in iOS 12.0: Use +unarchivedObjectOfClass:fromData:error: instead

line 302:
'archivedData(withRootObject:)' was deprecated in iOS 12.0: Use +archivedDataWithRootObject:requiringSecureCoding:error: instead

[dingwilson]

Thanks for reporting @thoughtcastapp! I have been pretty busy recently and have not had a chance to update this. I will try to get to this when I have a chance. I also welcome contributions from others, if you or someone else is interested in fixing this and submitting a PR with the changes. 👍