fix navbar shadow

@@ -52,7 +52,15 @@ extension UIViewController {
         navigationItem.standardAppearance = navigationBarAppearance
         navigationItem.compactAppearance = navigationBarAppearance
         navigationItem.scrollEdgeAppearance = navigationBarAppearance
+    }
+    
+    
+    @objc func moveToBack(_ sender:UIButton){
+        self.navigationController?.popViewController(animated: true)
+        self.dismiss(animated: true, completion: {})
+    }
 
+    func addNavShadow() {
         // Add shadow
         self.navigationController?.navigationBar.layer.masksToBounds = false
         self.navigationController?.navigationBar.layer.shadowColor = UIColor.lightGray.cgColor
@@ -61,12 +69,6 @@ extension UIViewController {
         self.navigationController?.navigationBar.layer.shadowRadius = 2
     }
     
-    
-    @objc func moveToBack(_ sender:UIButton){
-        self.navigationController?.popViewController(animated: true)
-        self.dismiss(animated: true, completion: {})
-    }
-    
     func setNavigationTitle(_ title: String, _ fontWeight: String? = "medium") {
         let uiscreen: CGRect = UIScreen.main.bounds
         

@@ -292,6 +292,8 @@ import SwiftEventBus
     public override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
 
+        addNavShadow()
+        
         let userTag = swiftApi().getUserTag()
         if (questionnaireButton.currentTitle != userTag) {
             if (userTag != "" && userTag != "undefined") {
@@ -327,6 +329,15 @@ import SwiftEventBus
 
         self.coupons = swiftApi().getCouponList()
         self.tableView.reloadData()
+
+        self.startTimer()
+    }
+
+    public override func viewWillDisappear(_ animated: Bool) {
+        super.viewWillDisappear(animated)
+
+        self.stopTimer()
+        self.navigationController?.navigationBar.layer.shadowOpacity = 0.0
     }
 
     public override func viewDidLayoutSubviews() {