Implement fail-safe mechanism if key id is not found

pass/Extensions/UIAlertActionExtension.swift

@@ -0,0 +1,44 @@
+//
+//  UIAlertActionExtension.swift
+//  passKit
+//
+//  Created by Sun, Mingshen on 4/17/20.
+//  Copyright © 2020 Bob Sun. All rights reserved.
+//
+
+import UIKit
+import Foundation
+import passKit
+
+extension UIAlertAction {
+    static func cancelAndPopView(controller: UIViewController) -> UIAlertAction {
+        UIAlertAction(title: "Cancel".localize(), style: .cancel) { _ in
+            controller.navigationController?.popViewController(animated: true)
+        }
+    }
+
+    static func cancel() -> UIAlertAction {
+        cancel(with: "Cancel")
+    }
+
+    static func dismiss() -> UIAlertAction {
+        cancel(with: "Dismiss")
+    }
+
+    static func cancel(with title: String) -> UIAlertAction {
+        UIAlertAction(title: "Cancel".localize(), style: .cancel, handler: nil)
+    }
+
+    static func selectKey(controller: UIViewController, handler: ((UIAlertAction) -> Void)?) -> UIAlertAction {
+        UIAlertAction(title: "Select Key", style: .default) { _ in
+            let selectKeyAlert = UIAlertController(title: "Select from imported keys", message: nil, preferredStyle: .actionSheet)
+            try? PGPAgent.shared.getShortKeyID().forEach({ k in
+                let action = UIAlertAction(title: k, style: .default, handler: handler)
+                selectKeyAlert.addAction(action)
+            })
+            selectKeyAlert.addAction(UIAlertAction.cancelAndPopView(controller: controller))
+            controller.present(selectKeyAlert, animated: true, completion: nil)
+        }
+    }
+
+}