Rewrote lots of bad "async" code

Code that should've been fully async that was not previously actually async, such as the networking code, is now actually async. This makes it much easier to read and means that it makes a lot more sense in the context of the program. This also means that all uses of DispatchQueue.main.sync{} and DispatchQueue.main.async{} are now gone.
DetailView's fetching code benefitted the most from these changes, and is now just one iterative function instead of two cursed functions involving callbacks. As a result, you can now also pull down on the detail view to refresh the data, which is handy. Note that occupancy isn't updated when doing this currently due to a task issue I haven't figured out yet, but you can just go back out and in to update that anyway.
ContentView will also now automatically refresh the data if the last refreshed date is no longer today, so if you let the app sit in the background and then focus it, dates should automatically update to being for today.

RIT Dining/Data/FetchData.swift

@@ -11,117 +11,88 @@ enum InvalidHTTPError: Error {
     case invalid
 }
 
-// This API requesting code came from another project of mine and was used to fetch the GitHub API for update checking. I just copied it
-// here, but it can probably be made simpler for this use case.
-
+// This code has now been mostly rewritten to be pretty and async instead of being horrifying callback based code in a context where
+// callback based code made no sense. I love async!
 // Get information for all dining locations.
-func getAllDiningInfo(date: String?, completionHandler: @escaping (Result<DiningLocationsParser, Error>) -> Void) {
+func getAllDiningInfo(date: String?) async -> Result<DiningLocationsParser, Error> {
     // The endpoint requires that you specify a date, so get today's.
-    let date_string: String = date ?? getAPIFriendlyDateString(date: Date())
-    let url_string = "https://tigercenter.rit.edu/tigerCenterApi/tc/dining-all?date=\(date_string)"
+    let dateString: String = date ?? getAPIFriendlyDateString(date: Date())
+    let urlString = "https://tigercenter.rit.edu/tigerCenterApi/tc/dining-all?date=\(dateString)"
     
-    guard let url = URL(string: url_string) else {
-        print("Invalid URL")
-        return
+    guard let url = URL(string: urlString) else {
+        return .failure(URLError(.badURL))
     }
-    let request = URLRequest(url: url)
-    
-    URLSession.shared.dataTask(with: request) { data, response, error in
-        if let error = error {
-            completionHandler(.failure(error))
-            return
+
+    do {
+        let (data, response) = try await URLSession.shared.data(from: url)
+        
+        guard let httpResponse = response as? HTTPURLResponse,
+              (200...299).contains(httpResponse.statusCode) else {
+            return .failure(InvalidHTTPError.invalid)
         }
         
-        guard let data = data else {
-            completionHandler(.failure(URLError(.badServerResponse)))
-            return
-        }
-        
-        guard let httpResponse = response as? HTTPURLResponse, (200...299).contains(httpResponse.statusCode) else {
-            completionHandler(.failure(InvalidHTTPError.invalid))
-            return
-        }
-        
-        let decoded: Result<DiningLocationsParser, Error> = Result(catching: { try JSONDecoder().decode(DiningLocationsParser.self, from: data) })
-        completionHandler(decoded)
-    }.resume()
+        let decoded = try JSONDecoder().decode(DiningLocationsParser.self, from: data)
+        return .success(decoded)
+    } catch {
+        return .failure(error)
+    }
 }
 
 // Get information for just one dining location based on its location ID.
-func getSingleDiningInfo(date: String?, locationId: Int, completionHandler: @escaping (Result<DiningLocationParser, Error>) -> Void) {
+func getSingleDiningInfo(date: String?, locId: Int) async -> Result<DiningLocationParser, Error> {
     // The current date and the location ID are required to get information for just one location.
-    let date_string: String = date ?? getAPIFriendlyDateString(date: Date())
-    let url_string = "https://tigercenter.rit.edu/tigerCenterApi/tc/dining-single?date=\(date_string)&locId=\(locationId)"
-    print("making request to \(url_string)")
-    
-    guard let url = URL(string: url_string) else {
-        print("Invalid URL")
-        return
+    let dateString: String = date ?? getAPIFriendlyDateString(date: Date())
+    let urlString = "https://tigercenter.rit.edu/tigerCenterApi/tc/dining-single?date=\(dateString)&locId=\(locId)"
+    print("making request to \(urlString)")
+
+    guard let url = URL(string: urlString) else {
+        return .failure(URLError(.badURL))
     }
-    let request = URLRequest(url: url)
-    
-    URLSession.shared.dataTask(with: request) { data, response, error in
-        if let error = error {
-            completionHandler(.failure(error))
-            return
+
+    do {
+        let (data, response) = try await URLSession.shared.data(from: url)
+        
+        guard let httpResponse = response as? HTTPURLResponse,
+              (200...299).contains(httpResponse.statusCode) else {
+            return .failure(InvalidHTTPError.invalid)
         }
         
-        guard let data = data else {
-            completionHandler(.failure(URLError(.badServerResponse)))
-            return
-        }
-        
-        guard let httpResponse = response as? HTTPURLResponse, (200...299).contains(httpResponse.statusCode) else {
-            completionHandler(.failure(InvalidHTTPError.invalid))
-            return
-        }
-        
-        let decoded: Result<DiningLocationParser, Error> = Result(catching: { try JSONDecoder().decode(DiningLocationParser.self, from: data) })
-        completionHandler(decoded)
-    }.resume()
+        let decoded = try JSONDecoder().decode(DiningLocationParser.self, from: data)
+        return .success(decoded)
+    } catch {
+        return .failure(error)
+    }
 }
 
-// Get the occupancy information for a location using its MDO ID, whatever that stands for. This ID is provided alongside the other main
-// ID in the data returned by the TigerCenter API.
-func getOccupancyPercentage(mdoId: Int, completionHandler: @escaping (Result<Double, Error>) -> Void) {
+// Get the occupancy information for a location using its MDO ID, whatever that stands for. This ID is provided alongside the other
+// main ID in the data returned by the TigerCenter API.
+func getOccupancyPercentage(mdoId: Int) async -> Result<Double, Error> {
     let urlString = "https://maps.rit.edu/proxySearch/densityMapDetail.php?mdo=\(mdoId)"
     print("making request to \(urlString)")
     
     guard let url = URL(string: urlString) else {
-        print("Invalid URL")
-        return
+        return .failure(URLError(.badURL))
     }
-    let occRequest = URLRequest(url: url)
     
-    URLSession.shared.dataTask(with: occRequest) { data, response, error in
-        if let error = error {
-            completionHandler(.failure(error))
-            return
+    do {
+        let (data, response) = try await URLSession.shared.data(from: url)
+        
+        guard let httpResponse = response as? HTTPURLResponse,
+              (200...299).contains(httpResponse.statusCode) else {
+            return .failure(InvalidHTTPError.invalid)
         }
         
-        guard let data = data else {
-            completionHandler(.failure(URLError(.badServerResponse)))
-            return
+        let occupancy = try JSONDecoder().decode([DiningOccupancyParser].self, from: data)
+        if !occupancy.isEmpty {
+            print("current occupancy: \(occupancy[0].count)")
+            print("maximum occupancy: \(occupancy[0].max_occ)")
+            let occupancyPercentage = Double(occupancy[0].count) / Double(occupancy[0].max_occ) * 100
+            print("occupancy percentage: \(occupancyPercentage)%")
+            return .success(occupancyPercentage)
+        } else {
+            return .failure(DecodingError.dataCorrupted(DecodingError.Context(codingPath: [], debugDescription: "Failed to decode JSON")))
         }
-        
-        guard let httpResponse = response as? HTTPURLResponse, (200...299).contains(httpResponse.statusCode) else {
-            completionHandler(.failure(InvalidHTTPError.invalid))
-            return
-        }
-        
-        do {
-            let occupancy = try JSONDecoder().decode([DiningOccupancyParser].self, from: data)
-            if !occupancy.isEmpty {
-                print("current occupancy: \(occupancy[0].count)")
-                print("maximum occupancy: \(occupancy[0].max_occ)")
-                let occupancyPercentage = Double(occupancy[0].count) / Double(occupancy[0].max_occ) * 100
-                print("occupancy percentage: \(occupancyPercentage)%")
-                completionHandler(.success(occupancyPercentage))
-            } else {
-                completionHandler(.failure(DecodingError.dataCorrupted(DecodingError.Context(codingPath: [], debugDescription: "Failed to decode JSON"))))
-            }
-        } catch {
-            completionHandler(.failure(DecodingError.dataCorrupted(DecodingError.Context(codingPath: [], debugDescription: "Failed to decode JSON"))))
-        }
-    }.resume()
+    } catch {
+        return .failure(error)
+    }
 }