Update an older IOS app to IOS11 and ARKit

I have an older IOS app which was used to collect the start and finish times of boats during sailboat races, take a photo at the start of the race and as boats were finishing; and email or otherwise push the results and photos to a server. The app was complete, but buggy, and was not yet released. The developer has moved on some time ago. The app does the following: 1) create fleets - each group of racers is put into a 'fleet' with some details about their boat and their numeric handicap rating. Basically, a CSV, one line per boat, which is either filled out in the app, or can be uploaded from a file. A race will typically have multiple fleets, each having multiple boats in the fleet. 2) run a race - there is a 'start' button to start each 'fleet', with the option to take a photo at the start. The fleet's yachts are then 'racing' and a timer is capturing the racing time. The yachts typically will finish at separate times and a button is clicked on the app next to the yacht's name to capture the finish time. Optionally, a photo of the finish time can be taken. 3) view results - there is a separate function to view the results of the race. The race has simple math of the elapsed time +/- the boat's handicap per mile to determine the 'corrected time'; the boat with the lowest corrected time wins the fleet. This is simple spreadsheet stuff. 4) advanced - this screen has the setup to upload results / photos / etc to a server, website, or social media. It also has a few adjustments which can be made to the race scoring calculation (mentioned above). The app still builds and installs in IOS10 but crashes; it won't build on the latest Xcode. It last worked in IOS9 and was 90% functional. I'd like to update the code base to work with IOS11. Also, the photo-taking capability, which involved using a text overlay on the camera's viewfinder display, seems like a good use case to move to ARkit so I'd like that approach updated as well. I have the original design documentation and screen mock-ups along with functionality explanations which can be shared. Once this is working there are a lot of enhancements I'd like to add to the app going forward, but to start the baseline functionality is the goal.