DelayedSaveStorage: only use cached data while saving is in progress.

DelayedSaveStorage/DelayedSaveStorage/DelayedSaveStorage.swift

@@ -54,24 +54,29 @@ public class DelayedSaveStorage: Storage {
             self?.latestKnownAppData = AppData(selectedIndex: selectedIndex, locations: locations)
         }
         saveDelayQueue.cancelAllOperations()
-        let saveOperation = BlockOperation()
-        saveOperation.addExecutionBlock { [weak saveOperation, weak self] in
-            guard saveOperation?.isCancelled == false else {
+        let saveWithDelayOperation = BlockOperation()
+        saveWithDelayOperation.addExecutionBlock { [weak saveWithDelayOperation, weak self] in
+            guard saveWithDelayOperation?.isCancelled == false else {
                 return
             }
             if let delay = self?.delay, delay > 0 {
                 Thread.sleep(forTimeInterval: delay)
             }
-            guard saveOperation?.isCancelled == false else {
+            guard saveWithDelayOperation?.isCancelled == false else {
                 return
             }
-            self?.saveQueue.addOperation {
-                if saveOperation?.isCancelled != true {
+            let saveOperation = BlockOperation()
+            saveOperation.addExecutionBlock { [weak saveOperation, weak self] in
+                guard saveWithDelayOperation?.isCancelled != true && saveOperation?.isCancelled != true else {
+                    return
+                }
+                self?.latestKnownAppDataSynchronizationQueue.addOperation {
                     self?.storage.save(locations: locations, selectedIndex: selectedIndex)
+                    self?.latestKnownAppData = nil
                 }
             }
         }
-        saveDelayQueue.addOperation(saveOperation)
+        saveDelayQueue.addOperation(saveWithDelayOperation)
     }
     
     public func load(completion: @escaping StorageCompletion) {