Use data and lock

FlagsmithClient/Classes/Flagsmith.swift

@@ -12,7 +12,7 @@ import FoundationNetworking
 
 /// Manage feature flags and remote config across multiple projects,
 /// environments and organisations.
-public class Flagsmith {
+public final class Flagsmith {
   /// Shared singleton client object
   public static let shared = Flagsmith()
   private let apiManager = APIManager()
@@ -263,7 +263,7 @@ public class Flagsmith {
   }
 }
 
-public class CacheConfig {
+public final class CacheConfig {
 
   /// Cache to use when enabled, defaults to the shared app cache
   public var cache: URLCache = URLCache.shared

FlagsmithClient/Classes/Internal/APIManager.swift

@@ -11,9 +11,11 @@ import FoundationNetworking
 #endif
 
 /// Handles interaction with a **Flagsmith** api.
-class APIManager : NSObject, URLSessionDataDelegate {
-  
+final class APIManager : NSObject, URLSessionDataDelegate {
+
   private var session: URLSession!
+  private let lock: NSLock = NSLock()
+  private let delegateQueue: OperationQueue = OperationQueue()
 
   /// Base `URL` used for requests.
   var baseURL = URL(string: "https://edge.api.flagsmith.com/api/v1/")!
@@ -22,22 +24,25 @@ class APIManager : NSObject, URLSessionDataDelegate {
 
   // store the completion handlers and accumulated data for each task
   private var tasksToCompletionHandlers:[URLSessionDataTask:(Result<Data, Error>) -> Void] = [:]
-  private var tasksToData:[URLSessionDataTask:NSMutableData] = [:]
+  private var tasksToData:[URLSessionDataTask:Data] = [:]
 
   override init() {
     super.init()
     let configuration = URLSessionConfiguration.default
-    self.session = URLSession(configuration: configuration, delegate: self, delegateQueue: OperationQueue.main)
+    delegateQueue.maxConcurrentOperationCount = 1
+    self.session = URLSession(configuration: configuration, delegate: self, delegateQueue: delegateQueue)
   }
 
   func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
     if let dataTask = task as? URLSessionDataTask {
+      lock.lock()
+      defer { lock.unlock() }
       if let completion = tasksToCompletionHandlers[dataTask] {
         if let error = error {
           completion(.failure(FlagsmithError.unhandled(error)))
         }
         else {
-          let data = tasksToData[dataTask] ?? NSMutableData()
+          let data = tasksToData[dataTask] ?? Data()
           completion(.success(data as Data))
         }
       }
@@ -47,7 +52,6 @@ class APIManager : NSObject, URLSessionDataDelegate {
   }
 
   func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, willCacheResponse proposedResponse: CachedURLResponse, completionHandler: @escaping (CachedURLResponse?) -> Void) {
-
     // intercept and modify the cache settings for the response
     if Flagsmith.shared.cacheConfig.useCache {
       let newResponse = proposedResponse.response(withExpirationDuration: Int(Flagsmith.shared.cacheConfig.cacheTTL))
@@ -58,7 +62,10 @@ class APIManager : NSObject, URLSessionDataDelegate {
   }
 
   func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
-    let existingData = tasksToData[dataTask] ?? NSMutableData()
+    lock.lock()
+    defer { lock.unlock() }
+
+    var existingData = tasksToData[dataTask] ?? Data()
     existingData.append(data)
     tasksToData[dataTask] = existingData
   }
@@ -98,8 +105,10 @@ class APIManager : NSObject, URLSessionDataDelegate {
     }
 
     // we must use the delegate form here, not the completion handler, to be able to modify the cache
+    lock.lock()
     let task = session.dataTask(with: request)
     tasksToCompletionHandlers[task] = completion
+    lock.unlock()
     task.resume()
   }
 

FlagsmithClient/Classes/Internal/FlagsmithAnalytics.swift

@@ -8,7 +8,7 @@
 import Foundation
 
 /// Internal analytics for the **FlagsmithClient**
-class FlagsmithAnalytics {
+final class FlagsmithAnalytics {
 
   /// Indicates if analytics are enabled.
   var enableAnalytics: Bool = true

FlagsmithClient/Classes/Internal/Router.swift

@@ -10,7 +10,7 @@ import Foundation
 import FoundationNetworking
 #endif
 
-enum Router {
+enum Router: Sendable {
   private enum HTTPMethod: String {
     case get = "GET"
     case post = "POST"