Fix a crash when iterating over the results of Realm.subscriptions()

CHANGELOG.md

@@ -1,3 +1,20 @@
+x.y.z Release notes (yyyy-MM-dd)
+=============================================================
+### Enhancements
+* None.
+
+### Fixed
+* Fix a crash when iterating over `Realm.subscriptions()` using for-in.
+  (Since 3.13.0, PR [#6050](https://github.com/realm/realm-cocoa/pull/6050)).
+
+### Compatibility
+* File format: Generates Realms with format v9 (Reads and upgrades all previous formats)
+* Realm Object Server: 3.11.0 or later.
+* APIs are backwards compatible with all previous releases in the 3.x.y series.
+
+### Internal
+* None.
+
 3.13.0 Release notes (2018-12-14)
 =============================================================
 

Realm/ObjectServerTests/SwiftObjectServerTests.swift

@@ -557,6 +557,10 @@ class SwiftObjectServerTests: SwiftSyncTestCase {
         let sub3 = realm.subscription(named: "query")!
         XCTAssertEqual(sub3.name, "query")
         XCTAssertEqual(sub3.state, .complete)
+        for sub in realm.subscriptions() {
+            XCTAssertEqual(sub.name, "query")
+            XCTAssertEqual(sub.state, .complete)
+        }
 
         XCTAssertNil(realm.subscription(named: "not query"))
     }

RealmSwift/RealmCollection.swift

@@ -43,7 +43,7 @@ public struct RLMIterator<Element: RealmCollectionValue>: IteratorProtocol {
             }
             return unsafeBitCast(next, to: Optional<Element>.self)
         }
-        return next as! Element?
+        return dynamicBridgeCast(fromObjectiveC: next as Any)
     }
 }