Don't use timezoneID, instead use timezone().

Clocker/Panel/Notes Popover/NotesPopover.swift

@@ -150,7 +150,7 @@ class NotesPopover: NSViewController {
     }
 
     private func getCurrentTimezoneDate(completionHandler: @escaping (_ response: Date?) -> Void) {
-        guard let timezoneID = dataObject?.timezoneID else {
+        guard let timezoneID = dataObject?.timezone() else {
             assertionFailure("Unable to retrieve timezoneID from the model")
             completionHandler(nil)
             return
@@ -353,7 +353,7 @@ class NotesPopover: NSViewController {
             let alertIndex = alertPopupButton.indexOfSelectedItem
 
             if eventCenter.createReminder(with: model.customLabel!,
-                                          timezone: model.timezoneID!,
+                                          timezone: model.timezone(),
                                           alertIndex: alertIndex,
                                           reminderDate: reminderPicker.dateValue,
                                           additionalNotes: model.note) {

Clocker/Preferences/General/PreferencesDataSource.swift

@@ -130,7 +130,7 @@ extension PreferencesDataSource: NSTableViewDataSource {
             return model.formattedAddress
         }
 
-        return model.timezoneID
+        return model.timezone()
     }
 
     func tableView(_: NSTableView, setObjectValue object: Any?, for _: NSTableColumn?, row: Int) {

Clocker/Preferences/General/PreferencesViewController.swift

@@ -633,7 +633,7 @@ extension PreferencesViewController {
 
         // Mark if the timezone is same as local timezone
         let timezoneObject = TimezoneData(with: newTimeZone)
-        timezoneObject.isSystemTimezone = timezoneObject.timezoneID == NSTimeZone.system.identifier
+        timezoneObject.isSystemTimezone = timezoneObject.timezone() == NSTimeZone.system.identifier
 
         let operationsObject = TimezoneDataOperations(with: timezoneObject)
         operationsObject.saveObject()
@@ -950,8 +950,8 @@ extension PreferencesViewController {
                 return false
             }
 
-            let timezone1 = NSTimeZone(name: object1.timezoneID!)
+            let timezone1 = NSTimeZone(name: object1.timezone())
-            let timezone2 = NSTimeZone(name: object2.timezoneID!)
+            let timezone2 = NSTimeZone(name: object2.timezone())
 
             let difference1 = system.secondsFromGMT() - timezone1!.secondsFromGMT
             let difference2 = system.secondsFromGMT() - timezone2!.secondsFromGMT