Move extension out of utils

passKit/Helpers/StringExtension.swift

@@ -0,0 +1,18 @@
+//
+//  StringExtension.swift
+//  passKit
+//
+//  Created by Yishi Lin on 2018/9/23.
+//  Copyright © 2018 Bob Sun. All rights reserved.
+//
+
+import Foundation
+
+public extension String {
+    func stringByAddingPercentEncodingForRFC3986() -> String? {
+        let unreserved = "-._~/?"
+        var allowed = CharacterSet.alphanumerics
+        allowed.insert(charactersIn: unreserved)
+        return addingPercentEncoding(withAllowedCharacters: allowed)
+    }
+}