Handle notifications for open conversations.

Signal/src/UserInterface/Notifications/AppNotifications.swift

@@ -648,7 +648,7 @@ class NotificationActionHandler {
         // can be visible to the user immediately upon opening the app, rather than having to watch
         // it animate in from the homescreen.
         let shouldAnimate = UIApplication.shared.applicationState == .active
-        signalApp.presentConversation(forThreadId: threadId, animated: shouldAnimate)
+        signalApp.presentConversationAndShowFirstUnreadMessage(forThreadId: threadId, animated: shouldAnimate)
         return Promise.value(())
     }
 

Signal/src/environment/SignalApp.h

@@ -46,7 +46,7 @@ NS_ASSUME_NONNULL_BEGIN
                       focusMessageId:(nullable NSString *)focusMessageId
                             animated:(BOOL)isAnimated;
 
-- (void)presentConversationForThreadAndShowFirstUnreadMessage:(TSThread *)thread animated:(BOOL)isAnimated;
+- (void)presentConversationAndShowFirstUnreadMessageForThreadId:(NSString *)threadId animated:(BOOL)isAnimated;
 
 #pragma mark - Methods
 

Signal/src/environment/SignalApp.m

@@ -122,14 +122,16 @@ NS_ASSUME_NONNULL_BEGIN
     });
 }
 
-- (void)presentConversationForThreadAndShowFirstUnreadMessage:(TSThread *)thread animated:(BOOL)isAnimated
+- (void)presentConversationAndShowFirstUnreadMessageForThreadId:(NSString *)threadId animated:(BOOL)isAnimated
 {
     OWSAssertIsOnMainThread();
+    OWSAssertDebug(threadId.length > 0);
 
     OWSLogInfo(@"");
 
-    if (!thread) {
-        OWSFailDebug(@"Can't present nil thread.");
+    TSThread *thread = [TSThread fetchObjectWithUniqueID:threadId];
+    if (thread == nil) {
+        OWSFailDebug(@"unable to find thread with id: %@", threadId);
         return;
     }