Avoid repaint by requestng contacts before Compose

This entailed passing callback params through the contact request.

// FREEBIE

Signal/src/ViewControllers/SignalsViewController.m

@@ -279,9 +279,18 @@ NSString *const SignalsViewControllerSegueShowIncomingCall = @"ShowIncomingCallS
 - (IBAction)composeNew
 {
     MessageComposeTableViewController *viewController = [MessageComposeTableViewController new];
-    UINavigationController *navigationController =
-        [[UINavigationController alloc] initWithRootViewController:viewController];
-    [self presentTopLevelModalViewController:navigationController animateDismissal:YES animatePresentation:YES];
+
+    [self.contactsManager requestSystemContactsOnceWithCompletion:^(NSError *_Nullable error) {
+        DDLogError(@"%@ Error when requesting contacts: %@", self.tag, error);
+        // Even if there was an error fetching contacts we proceed to the next screen.
+        // As the compose view will present the proper thing depending on contact access.
+        //
+        // We just want to make sure contact access is *complete* before showing the compose
+        // screen to avoid flicker.
+        UINavigationController *navigationController =
+            [[UINavigationController alloc] initWithRootViewController:viewController];
+        [self presentTopLevelModalViewController:navigationController animateDismissal:YES animatePresentation:YES];
+    }];
 }
 
 - (void)swappedSegmentedControl {

Signal/src/contact/OWSContactsManager.h

@@ -39,6 +39,7 @@ extern NSString *const OWSContactsManagerSignalAccountsDidChangeNotification;
 // Request systems contacts and start syncing changes. The user will see an alert
 // if they haven't previously.
 - (void)requestSystemContactsOnce;
+- (void)requestSystemContactsOnceWithCompletion:(void (^_Nullable)(NSError *_Nullable error))completion;
 
 // Ensure's the app has the latest contacts, but won't prompt the user for contact
 // access if they haven't granted it.

Signal/src/contact/OWSContactsManager.m

@@ -54,9 +54,15 @@ NSString *const OWSContactsManagerSignalAccountsDidChangeNotification =
 // Request contacts access if you haven't asked recently.
 - (void)requestSystemContactsOnce
 {
-    [self.systemContactsFetcher requestOnce];
+    [self requestSystemContactsOnceWithCompletion:nil];
 }
 
+- (void)requestSystemContactsOnceWithCompletion:(void (^_Nullable)(NSError *_Nullable error))completion
+{
+    [self.systemContactsFetcher requestOnceWithCompletion:completion];
+}
+
+
 - (void)fetchSystemContactsIfAlreadyAuthorized
 {
     [self.systemContactsFetcher fetchIfAlreadyAuthorized];

Signal/src/contact/SystemContactsFetcher.swift

@@ -39,11 +39,19 @@ class SystemContactsFetcher: NSObject {
         CNContactEmailAddressesKey as CNKeyDescriptor
     ]
 
-    public func requestOnce() {
+    /**
+     * Ensures we've requested access for system contacts. This can be used in multiple places,
+     * where we might need contact access, but will ensure we don't wastefully reload contacts
+     * if we have already fetched contacts.
+     *
+     * @param   completion  completion handler is called on main thread.
+     */
+    public func requestOnce(completion: ((Error?) -> Void)?) {
         AssertIsOnMainThread()
 
         guard !systemContactsHaveBeenRequestedAtLeastOnce else {
             Logger.debug("\(TAG) already requested system contacts")
+            completion?(nil)
             return
         }
         systemContactsHaveBeenRequestedAtLeastOnce = true
@@ -54,22 +62,32 @@ class SystemContactsFetcher: NSObject {
             contactStore.requestAccess(for: .contacts) { (granted, error) in
                 if let error = error {
                     Logger.error("\(self.TAG) error fetching contacts: \(error)")
-                    assertionFailure()
+                    DispatchQueue.main.async {
+                        completion?(error)
+                    }
                 }
 
                 guard granted else {
                     Logger.info("\(self.TAG) declined contact access.")
+                    // This case should have been caught be the error guard a few lines up.
+                    assertionFailure()
+                    DispatchQueue.main.async {
+                        completion?(nil)
+                    }
                     return
                 }
 
                 DispatchQueue.main.async {
-                    self.updateContacts()
+                    self.updateContacts(completion: completion)
                 }
             }
         case .authorized:
-            self.updateContacts()
+            self.updateContacts(completion: completion)
         case .denied, .restricted:
             Logger.debug("\(TAG) contacts were \(self.authorizationStatus)")
+            DispatchQueue.main.async {
+                completion?(nil)
+            }
         }
     }
 
@@ -79,10 +97,10 @@ class SystemContactsFetcher: NSObject {
             return
         }
 
-        updateContacts()
+        updateContacts(completion: nil)
     }
 
-    private func updateContacts() {
+    private func updateContacts(completion: ((Error?) -> Void)?) {
         AssertIsOnMainThread()
 
         systemContactsHaveBeenRequestedAtLeastOnce = true
@@ -100,11 +118,16 @@ class SystemContactsFetcher: NSObject {
             } catch let error as NSError {
                 Logger.error("\(self.TAG) Failed to fetch contacts with error:\(error)")
                 assertionFailure()
+                DispatchQueue.main.async {
+                    completion?(error)
+                }
+                return
             }
 
             let contacts = systemContacts.map { Contact(systemContact: $0) }
             DispatchQueue.main.async {
                 self.delegate?.systemContactsFetcher(self, updatedContacts: contacts)
+                completion?(nil)
             }
         }
     }
@@ -118,7 +141,7 @@ class SystemContactsFetcher: NSObject {
 
     @objc
     private func contactStoreDidChange() {
-        updateContacts()
+        updateContacts(completion: nil)
     }
 
 }