Fix Obj-C interop issue

SignalServiceKit/src/Loki/LokiAPI.swift

@@ -66,7 +66,7 @@ import PromiseKit
     }
     
     // MARK: Obj-C API
-    @objc public static func sendSignalMessage(_ signalMessage: SignalMessage, to destination: String, requiringPoW isPoWRequired: Bool, completionHandler: ((RawResponse?, NSError?) -> Void)? = nil) {
-        LokiMessage.fromSignalMessage(signalMessage, requiringPoW: isPoWRequired).then(sendMessage).done { completionHandler?($0, nil) }.catch { completionHandler?(nil, $0 as NSError) }
+    @objc public static func sendSignalMessage(_ signalMessage: SignalMessage, to destination: String, requiringPoW isPoWRequired: Bool, completionHandler: @escaping (RawResponse?, NSError?) -> Void) {
+        LokiMessage.fromSignalMessage(signalMessage, requiringPoW: isPoWRequired).then(sendMessage).done { completionHandler($0, nil) }.catch { completionHandler(nil, $0 as NSError) }
     }
 }

SignalServiceKit/src/Loki/LokiMessage.swift

@@ -25,8 +25,8 @@ public struct LokiMessage {
     public static func fromSignalMessage(_ signalMessage: SignalMessage, requiringPoW isPoWRequired: Bool) -> Promise<LokiMessage> {
         return Promise<LokiMessage> { seal in
             DispatchQueue.global(qos: .default).async {
-                let destination = signalMessage["destination"]!
-                let data = signalMessage["content"]!
+                let destination = signalMessage["destination"] as! String
+                let data = signalMessage["content"] as! String
                 let ttl = LokiAPI.defaultMessageTTL
                 if isPoWRequired {
                     let timestamp = UInt64(Date().timeIntervalSince1970)

SignalServiceKit/src/Loki/SignalMessage.swift

@@ -1,2 +1,2 @@
 
-public typealias SignalMessage = [String:String]
+public typealias SignalMessage = [String:Any]

SignalServiceKit/src/Messages/OWSMessageSender.m

@@ -1111,7 +1111,9 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
     // Convert the message to a Loki message and send it using the Loki messaging API
     NSDictionary *signalMessage = deviceMessages.firstObject;
     BOOL isPoWRequired = YES; // TODO: Base on message type
-    [LokiAPI sendSignalMessage:signalMessage to:recipient.recipientId requiringPoW:isPoWRequired completionHandler:nil];
+    [LokiAPI sendSignalMessage:signalMessage to:recipient.recipientId requiringPoW:isPoWRequired completionHandler:^(id response, NSError *error) {
+        // TODO: Use the response
+    }];
     
     // Loki: Original code
     /*