fix: Make code compatible with macOS. (#900)

* fix: Remove unconditional iOS requirements.

* Fix linter error

---------

Co-authored-by: Artur Jankowski <[email protected]>

Author: jlawton

Sources/Core/BoxJSONDecoder.swift

@@ -7,7 +7,6 @@
 //
 
 import Foundation
-import UIKit
 
 // swiftlint:disable:next convenience_type
 class BoxJSONDecoder {
@@ -152,12 +151,12 @@ class BoxJSONDecoder {
         return url
     }
 
-    static func optionalDecodeColor(json: [String: Any], forKey key: String) throws -> UIColor? {
+    static func optionalDecodeColor(json: [String: Any], forKey key: String) throws -> PlatformColor? {
         guard let value: String = try optionalExtractJSON(json: json, key: key), !value.isEmpty else {
             return nil
         }
 
-        guard let color = UIColor(hex: value) else {
+        guard let color = PlatformColor(hex: value) else {
             throw BoxCodingError(message: .invalidValueFormat(key: key))
         }
 

Sources/Core/Extensions/UIColorExtension.swift

@@ -6,9 +6,19 @@
 //  Copyright © 2020 box. All rights reserved.
 //
 
-import UIKit
+#if canImport(UIKit)
+  import UIKit
 
-extension UIColor {
+  /// The color type used natively on the target platform.
+  public typealias PlatformColor = UIColor
+#elseif canImport(AppKit)
+  import AppKit
+
+  /// The color type used natively on the target platform.
+  public typealias PlatformColor = NSColor
+#endif
+
+extension PlatformColor {
     convenience init?(hex: String) {
         let red, green, blue, alpha: CGFloat
         if hex.hasPrefix("#") {

Sources/Core/MimeTypeProvider.swift

@@ -7,14 +7,13 @@
 //
 
 import Foundation
-#if os(iOS)
-    #if canImport(UniformTypeIdentifiers)
-        import UniformTypeIdentifiers
-    #endif
-
-    #if canImport(MobileCoreServices)
-        import MobileCoreServices
-    #endif
+
+#if canImport(UniformTypeIdentifiers)
+    import UniformTypeIdentifiers
+#endif
+
+#if canImport(MobileCoreServices)
+    import MobileCoreServices
 #endif
 
 /// Provides method for converting given filename to mime type

Sources/Modules/FoldersModule+Async.swift

@@ -7,7 +7,6 @@
 //
 
 import Foundation
-import UIKit
 
 @available(iOS 13.0, *)
 public extension FoldersModule {

Sources/Responses/Classification.swift

@@ -7,15 +7,14 @@
 //
 
 import Foundation
-import UIKit
 
 /// Details about the classification applied to a Box file or folder
 public class Classification: BoxModel {
     // MARK: - Properties
 
     public private(set) var rawData: [String: Any]
     /// The color that is used to display the classification label in a user-interface
-    public let color: UIColor?
+    public let color: PlatformColor?
     /// An explanation of the meaning of this classification
     public let definition: String?
     /// Name of the classification