project: conform to a swifty way of coding

This commit:
- adapts code to a more Swifty way of coding
- uses previously added frameworks to make the code "type safer"

Change-Id: I5332e2843e82cac4f4f9af79714993863ef5963d
diff --git a/Ring/.swiftlint.yml b/Ring/.swiftlint.yml
index 07e9a65..fab1ed2 100644
--- a/Ring/.swiftlint.yml
+++ b/Ring/.swiftlint.yml
@@ -1,4 +1,5 @@
 disabled_rules: # rule identifiers to exclude from running
+  - todo
 
 opt_in_rules: # some rules are only opt-in
   - empty_count