Activity tracker functionality for an iOS app in Swift 4

I'm in mid-development of an app for iOS. I need to finalize some core functionality within the next 1-2 weeks and require help to achieve this. I need someone that have experience with best practice activity tracker functionality for iOS. It is important that the functionality is battery and data efficient and can handle offline situations (eg. Store locally for uploading once back online) . This is only a part of an app, so it needs to tie in with other functionality. The key function is an activity tracker, GIS processing and data handling. In addition, real time location sharing should be implemented for users within a club. And waypoints stored along the route for certain activities (take a photo, animal seen etc). The design is mostly ready in storyboard, but some elements needs to be solved eg. Dynamic input form. Other functions that will be needed are, image upload, dynamic input forms, cache map for offline use, deferredLocationUpdatedAvailable to save battery, I have a suggestion for data structure, but I would like your input as to improve data efficiency and scalability. Requirements are Swift 4 for compatibility with iOS 11. Utilizing Firebase as the [login to view URL] portrait mode. Code should be well documented. Pods that might be useful - SwiftSimplify - GEOSwift I have additional descriptions of the functionality to share if you are interested