Use iOS localization handling for strings. (#803)

ElementX/Sources/Other/Extensions/Bundle.swift

@@ -17,43 +17,7 @@
 import Foundation
 
 public extension Bundle {
-    private static var cachedLocalizationBundles = [String: Bundle]()
-    
-    /// Get an lproj language bundle from the receiver bundle.
-    /// - Parameter language: The language to try to load.
-    /// - Returns: The lproj bundle if found otherwise nil.
-    func lprojBundle(for language: String) -> Bundle? {
-        if let bundle = Self.cachedLocalizationBundles[language] {
-            return bundle
-        }
-        
-        guard let lprojURL = Bundle.app.url(forResource: language, withExtension: "lproj") else {
-            return nil
-        }
-        
-        let bundle = Bundle(url: lprojURL)
-        Self.cachedLocalizationBundles[language] = bundle
-        
-        return bundle
-    }
-
-    /// Preferred app language for translations. Takes the highest priority in translations. The priority list for translations:
-    /// - `Bundle.elementLanguage`
-    /// - `Locale.preferredLanguages`
-    /// - `Bundle.elementFallbackLanguage`
-    static var elementLanguage: String? {
-        didSet {
-            preferredLanguages = calculatePreferredLanguages()
-        }
-    }
-
-    /// Preferred fallback language for translations. Only used for strings not translated neither to `elementLanguage` nor to one of the user's preferred languages.
-    static var elementFallbackLanguage: String? {
-        didSet {
-            preferredLanguages = calculatePreferredLanguages()
-        }
-    }
-
+    /// The top-level bundle that contains the entire app.
     static var app: Bundle {
         var bundle = Bundle.main
         if bundle.bundleURL.pathExtension == "appex" {
@@ -65,16 +29,29 @@ public extension Bundle {
         }
         return bundle
     }
-
-    /// Preferred languages in the priority order.
-    private(set) static var preferredLanguages: [String] = calculatePreferredLanguages()
-
-    private static func calculatePreferredLanguages() -> [String] {
-        var set = Set<String>()
-        return ([Bundle.elementLanguage] +
-            Locale.preferredLanguages +
-            [Bundle.elementFallbackLanguage])
-            .compactMap { $0 }
-            .filter { set.insert($0).inserted }
+    
+    // MARK: - Localisation
+    
+    private static var cachedLocalizationBundles = [String: Bundle]()
+    
+    /// Get an lproj language bundle from the receiver bundle.
+    /// - Parameter language: The language to try to load.
+    /// - Returns: The lproj bundle if found otherwise nil.
+    static func lprojBundle(for language: String) -> Bundle? {
+        if let bundle = cachedLocalizationBundles[language] {
+            return bundle
+        }
+        
+        guard let lprojURL = Bundle.app.url(forResource: language, withExtension: "lproj") else {
+            return nil
+        }
+        
+        let bundle = Bundle(url: lprojURL)
+        cachedLocalizationBundles[language] = bundle
+        
+        return bundle
     }
+
+    /// Overrides `Bundle.app.preferredLocalizations` for testing translations.
+    static var overrideLocalizations: [String]?
 }