Extract key importing logic and put it into separate class

passKit/Helpers/KeyFileManager.swift

@@ -0,0 +1,40 @@
+//
+//  KeyFileManager.swift
+//  passKit
+//
+//  Created by Danny Moesch on 29.06.19.
+//  Copyright © 2019 Bob Sun. All rights reserved.
+//
+
+public class KeyFileManager {
+    public typealias KeyHandler = (Data, String) -> ()
+
+    public static let PublicPgp = KeyFileManager(keyType: PgpKeyType.PUBLIC)
+    public static let PrivatePgp = KeyFileManager(keyType: PgpKeyType.PRIVATE)
+
+    private let keyType: PgpKeyType
+    private let keyPath: String
+    private let keyHandler: KeyHandler
+
+    private convenience init(keyType: PgpKeyType) {
+        self.init(keyType: keyType, keyPath: keyType.getFileSharingPath())
+    }
+
+    public init(keyType: PgpKeyType, keyPath: String, keyHandler: @escaping KeyHandler = AppKeychain.add) {
+        self.keyType = keyType
+        self.keyPath = keyPath
+        self.keyHandler = keyHandler
+    }
+
+    public func importKeyAndDeleteFile() throws {
+        guard let keyFileContent = FileManager.default.contents(atPath: keyPath) else {
+            throw AppError.ReadingFile(URL(fileURLWithPath: keyPath).lastPathComponent)
+        }
+        keyHandler(keyFileContent, keyType.getKeychainKey())
+        try FileManager.default.removeItem(atPath: keyPath)
+    }
+    
+    public func doesKeyFileExist() -> Bool {
+        return FileManager.default.fileExists(atPath: keyPath)
+    }
+}