[LOOP-1003] get context update first, then glucose backfill (#402)

Author: nhamming

WatchApp Extension/Controllers/HUDInterfaceController.swift

@@ -29,9 +29,10 @@ class HUDInterfaceController: WKInterfaceController {
                 }
             }
         }
-        
-        loopManager.requestGlucoseBackfillIfNecessary()
-        loopManager.requestContextUpdate()
+
+        loopManager.requestContextUpdate(completion: {
+            self.loopManager.requestGlucoseBackfillIfNecessary()
+        })
     }
 
     override func didDeactivate() {

WatchApp Extension/Managers/LoopDataManager.swift

@@ -166,7 +166,7 @@ extension LoopDataManager {
         return true
     }
 
-    func requestContextUpdate() {
+    func requestContextUpdate(completion: @escaping () -> Void = { }) {
         try? WCSession.default.sendContextRequestMessage(WatchContextRequestUserInfo(), completionHandler: { (result) in
             DispatchQueue.main.async {
                 switch result {
@@ -175,6 +175,7 @@ extension LoopDataManager {
                 case .failure:
                     break
                 }
+                completion()
             }
         })
     }