Merge pull request #175 from mattrubin/swiftlint

Enable several new SwiftLint opt-in rules

.swiftlint.yml

@@ -11,7 +11,9 @@ opt_in_rules:
   - contains_over_first_not_nil
   - discouraged_object_literal
   - discouraged_optional_boolean
+  - discouraged_optional_collection
   - empty_count
+  - empty_string
   - explicit_enum_raw_value
   - explicit_init
   - extension_access_modifier
@@ -23,6 +25,7 @@ opt_in_rules:
   - joined_default_parameter
   - let_var_whitespace
   - literal_expression_end_indentation
+  - lower_acl_than_parent
   - multiline_parameters
   - nimble_operator
   - operator_usage_whitespace
@@ -36,6 +39,7 @@ opt_in_rules:
   - sorted_first_last
   - switch_case_on_newline
   - unneeded_parentheses_in_closure_argument
+  - untyped_error_in_catch
   - vertical_parameter_alignment_on_call
   - yoda_condition
 disabled_rules: