use existing Utils method to copy array of message ids

deltachat-ios/DC/Wrapper.swift

@@ -49,11 +49,8 @@ class DcContext {
         guard let messagesPointer = dc_get_chat_media(contextPointer, UInt32(chatId), messageType, messageType2, messageType3) else {
             return []
         }
-        let array = DcArray(arrayPointer: messagesPointer)
-        var messageIds: [Int] = []
-        for index in 0..<array.count {
-            messageIds.append(array.getId(at: index))
-        }
+
+        let messageIds: [Int] =  Utils.copyAndFreeArray(inputArray: messagesPointer)
         return messageIds
     }
 
@@ -568,10 +565,6 @@ class DcArray {
        return Int(dc_array_get_cnt(dcArrayPointer))
     }
 
-    func getId(at index: Int) -> Int {
-        return Int(dc_array_get_id(dcArrayPointer, index))
-    }
-
     ///TODO: add missing methods here
 }