Implement share/activity button on iOS

Multiplatform/iOS/Article/TitleActivityItemSource.swift

@@ -0,0 +1,40 @@
+//
+//  TitleActivityItemSource.swift
+//  Multiplatform iOS
+//
+//  Created by Maurice Parker on 7/13/20.
+//  Copyright © 2020 Ranchero Software. All rights reserved.
+//
+
+import UIKit
+
+class TitleActivityItemSource: NSObject, UIActivityItemSource {
+
+	private let title: String?
+
+	init(title: String?) {
+		self.title = title
+	}
+
+	func activityViewControllerPlaceholderItem(_ activityViewController: UIActivityViewController) -> Any {
+		return title as Any
+	}
+
+	func activityViewController(_ activityViewController: UIActivityViewController, itemForActivityType activityType: UIActivity.ActivityType?) -> Any? {
+		guard let activityType = activityType,
+			let title = title else {
+				return NSNull()
+		}
+
+		switch activityType.rawValue {
+		case "com.omnigroup.OmniFocus3.iOS.QuickEntry",
+			 "com.culturedcode.ThingsiPhone.ShareExtension",
+			 "com.tapbots.Tweetbot4.shareextension",
+			 "com.buffer.buffer.Buffer":
+			return title
+		default:
+			return NSNull()
+		}
+	}
+	
+}