Convert backup logic to use promises.

Signal/src/ViewControllers/AppSettings/OWSBackupSettingsViewController.m

@@ -74,16 +74,16 @@ NS_ASSUME_NONNULL_BEGIN
     __weak OWSBackupSettingsViewController *weakSelf = self;
     [[self.backup checkCloudKitAccess]
             .then(^{
-                dispatch_async(dispatch_get_main_queue(), ^{
-                    weakSelf.iCloudError = nil;
-                    [weakSelf updateTableContents];
-                });
+                OWSAssertIsOnMainThread();
+
+                weakSelf.iCloudError = nil;
+                [weakSelf updateTableContents];
             })
             .catch(^(NSError *error) {
-                dispatch_async(dispatch_get_main_queue(), ^{
-                    weakSelf.iCloudError = error;
-                    [weakSelf updateTableContents];
-                });
+                OWSAssertIsOnMainThread();
+
+                weakSelf.iCloudError = error;
+                [weakSelf updateTableContents];
             }) retainUntilComplete];
 }
 

Signal/src/ViewControllers/DebugUI/DebugUIBackup.m

@@ -90,16 +90,14 @@ NS_ASSUME_NONNULL_BEGIN
     NSString *recipientId = self.tsAccountManager.localNumber;
     [[self.backup checkCloudKitAccess]
             .then(^{
-                dispatch_async(dispatch_get_main_queue(), ^{
-                    [OWSBackupAPI saveTestFileToCloudWithRecipientId:recipientId
-                                                             fileUrl:[NSURL fileURLWithPath:filePath]
-                                                             success:^(NSString *recordName) {
-                                                                 // Do nothing, the API method will log for us.
-                                                             }
-                                                             failure:^(NSError *error){
-                                                                 // Do nothing, the API method will log for us.
-                                                             }];
-                });
+                [OWSBackupAPI saveTestFileToCloudWithRecipientId:recipientId
+                                                         fileUrl:[NSURL fileURLWithPath:filePath]
+                                                         success:^(NSString *recordName) {
+                                                             // Do nothing, the API method will log for us.
+                                                         }
+                                                         failure:^(NSError *error){
+                                                             // Do nothing, the API method will log for us.
+                                                         }];
             })
             .catch(^(NSError *error){
                 // Do nothing, the API method will log for us.

Signal/src/util/Backup/OWSBackup.m

@@ -474,7 +474,7 @@ NSArray<NSString *> *MiscCollectionsToBackup(void)
     }
 
     [[OWSBackupAPI checkCloudKitAccessObjc]
-            .then(^{
+            .thenInBackground(^{
                 [OWSBackupAPI checkForManifestInCloudWithRecipientId:recipientId
                     success:^(BOOL value) {
                         dispatch_async(dispatch_get_main_queue(), ^{
@@ -488,9 +488,7 @@ NSArray<NSString *> *MiscCollectionsToBackup(void)
                     }];
             })
             .catch(^(NSError *error) {
-                dispatch_async(dispatch_get_main_queue(), ^{
-                    failure(error);
-                });
+                failure(error);
             }) retainUntilComplete];
 }
 

Signal/src/util/Backup/OWSBackupExportJob.m

@@ -349,17 +349,13 @@ NS_ASSUME_NONNULL_BEGIN
 
     __weak OWSBackupExportJob *weakSelf = self;
     [[self.backup checkCloudKitAccess]
-            .then(^{
-                dispatch_async(dispatch_get_main_queue(), ^{
-                    [weakSelf start];
-                });
+            .thenInBackground(^{
+                [weakSelf start];
             })
             .catch(^(NSError *error) {
-                dispatch_async(dispatch_get_main_queue(), ^{
-                    [weakSelf failWithErrorDescription:
-                                  NSLocalizedString(@"BACKUP_EXPORT_ERROR_COULD_NOT_EXPORT",
-                                      @"Error indicating the backup export could not export the user's data.")];
-                });
+                [weakSelf failWithErrorDescription:
+                              NSLocalizedString(@"BACKUP_EXPORT_ERROR_COULD_NOT_EXPORT",
+                                  @"Error indicating the backup export could not export the user's data.")];
             }) retainUntilComplete];
 }
 

Signal/src/util/Backup/OWSBackupImportJob.m

@@ -78,17 +78,13 @@ NSString *const kOWSBackup_ImportDatabaseKeySpec = @"kOWSBackup_ImportDatabaseKe
 
     __weak OWSBackupImportJob *weakSelf = self;
     [[self.backup checkCloudKitAccess]
-            .then(^{
-                dispatch_async(dispatch_get_main_queue(), ^{
-                    [weakSelf start];
-                });
+            .thenInBackground(^{
+                [weakSelf start];
             })
             .catch(^(NSError *error) {
-                dispatch_async(dispatch_get_main_queue(), ^{
-                    [weakSelf failWithErrorDescription:
-                                  NSLocalizedString(@"BACKUP_IMPORT_ERROR_COULD_NOT_IMPORT",
-                                      @"Error indicating the backup import could not import the user's data.")];
-                });
+                [weakSelf failWithErrorDescription:
+                              NSLocalizedString(@"BACKUP_IMPORT_ERROR_COULD_NOT_IMPORT",
+                                  @"Error indicating the backup import could not import the user's data.")];
             }) retainUntilComplete];
 }