Send "disappearing messages" state for groups.

SignalServiceKit/src/Contacts/Threads/TSGroupThread.h

@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "TSGroupModel.h"
@@ -22,6 +22,7 @@ NS_ASSUME_NONNULL_BEGIN
 + (instancetype)getOrCreateThreadWithGroupId:(NSData *)groupId
                                  transaction:(YapDatabaseReadWriteTransaction *)transaction;
 
++ (nullable instancetype)threadWithGroupId:(NSData *)groupId;
 + (nullable instancetype)threadWithGroupId:(NSData *)groupId transaction:(YapDatabaseReadTransaction *)transaction;
 
 + (NSString *)threadIdFromGroupId:(NSData *)groupId;

SignalServiceKit/src/Contacts/Threads/TSGroupThread.m

@@ -1,5 +1,5 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "TSGroupThread.h"
@@ -58,6 +58,17 @@ NS_ASSUME_NONNULL_BEGIN
     return self;
 }
 
++ (nullable instancetype)threadWithGroupId:(NSData *)groupId;
+{
+    OWSAssert(groupId.length > 0);
+
+    __block TSGroupThread *thread;
+    [[self dbReadWriteConnection] readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+        thread = [self threadWithGroupId:groupId transaction:transaction];
+    }];
+    return thread;
+}
+
 + (nullable instancetype)threadWithGroupId:(NSData *)groupId transaction:(YapDatabaseReadTransaction *)transaction
 {
     OWSAssert(groupId.length > 0);

SignalServiceKit/src/Devices/OWSGroupsOutputStream.m

@@ -1,9 +1,13 @@
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
 
 #import "OWSGroupsOutputStream.h"
 #import "MIMETypeUtil.h"
+#import "OWSDisappearingMessagesConfiguration.h"
 #import "OWSSignalServiceProtos.pb.h"
 #import "TSGroupModel.h"
+#import "TSGroupThread.h"
 #import <ProtocolBuffers/CodedOutputStream.h>
 
 NS_ASSUME_NONNULL_BEGIN
@@ -33,6 +37,16 @@ NS_ASSUME_NONNULL_BEGIN
     [self.delegateStream writeRawVarint32:groupDataLength];
     [self.delegateStream writeRawData:groupData];
 
+    TSGroupThread *_Nullable groupThread = [TSGroupThread threadWithGroupId:group.groupId];
+    if (groupThread) {
+        OWSDisappearingMessagesConfiguration *_Nullable disappearingMessagesConfiguration =
+            [OWSDisappearingMessagesConfiguration fetchObjectWithUniqueID:groupThread.uniqueId];
+
+        if (disappearingMessagesConfiguration && disappearingMessagesConfiguration.isEnabled) {
+            [groupBuilder setExpireTimer:disappearingMessagesConfiguration.durationSeconds];
+        }
+    }
+
     if (avatarPng) {
         [self.delegateStream writeRawData:avatarPng];
     }