Force sync configuration upon enabling multi device or clearing data

Session/Meta/AppDelegate.swift

@@ -1,7 +1,9 @@
+import PromiseKit
 
 extension AppDelegate {
 
-    @objc func syncConfigurationIfNeeded() {
+    @objc(syncConfigurationIfNeeded)
+    func syncConfigurationIfNeeded() {
         let userDefaults = UserDefaults.standard
         guard userDefaults[.isUsingMultiDevice] else { return }
         let lastSync = userDefaults[.lastConfigurationSync] ?? .distantPast
@@ -13,4 +15,20 @@ extension AppDelegate {
             JobQueue.shared.add(job, using: transaction)
         }
     }
+
+    func forceSyncConfigurationNowIfNeeded() -> Promise<Void> {
+        let userDefaults = UserDefaults.standard
+        guard userDefaults[.isUsingMultiDevice] else { return Promise.value(()) }
+        let configurationMessage = ConfigurationMessage.getCurrent()
+        let destination = Message.Destination.contact(publicKey: getUserHexEncodedPublicKey())
+        let (promise, seal) = Promise<Void>.pending()
+        Storage.write { transaction in
+            MessageSender.send(configurationMessage, to: destination, using: transaction).done {
+                seal.fulfill(())
+            }.catch { _ in
+                seal.fulfill(()) // Fulfill even if this failed; the configuration in the swarm should be at most 2 days old
+            }.retainUntilComplete()
+        }
+        return promise
+    }
 }

Session/Settings/MultiDeviceVC.swift

@@ -148,6 +148,9 @@ final class MultiDeviceVC : BaseVC {
     // MARK: Interaction
     @objc private func handleToggle() {
         stepsRow.isHidden = !toggle.isOn
+        UserDefaults.standard[.isUsingMultiDevice] = toggle.isOn
+        let appDelegate = UIApplication.shared.delegate as! AppDelegate
+        appDelegate.forceSyncConfigurationNowIfNeeded().retainUntilComplete()
     }
 
     @objc private func copyMnemonic() {

Session/Settings/NukeDataModal.swift

@@ -50,8 +50,14 @@ final class NukeDataModal : Modal {
     // MARK: Interaction
     @objc private func nuke() {
         func proceed() {
-            UserDefaults.removeAll() // Not done in the nuke data implementation as unlinking requires this to happen later
-            NotificationCenter.default.post(name: .dataNukeRequested, object: nil)
+            let appDelegate = UIApplication.shared.delegate as! AppDelegate
+            ModalActivityIndicatorViewController.present(fromViewController: navigationController!, canCancel: false) { [weak self] _ in
+                appDelegate.forceSyncConfigurationNowIfNeeded().done(on: DispatchQueue.main) {
+                    self?.dismiss(animated: true, completion: nil) // Dismiss the loader
+                    UserDefaults.removeAll() // Not done in the nuke data implementation as unlinking requires this to happen later
+                    NotificationCenter.default.post(name: .dataNukeRequested, object: nil)
+                }.retainUntilComplete()
+            }
         }
         if KeyPairUtilities.hasV2KeyPair() {
             proceed()