mailto links now open on iOS

fixes #2036

Extends `URL` with an email address `var` for `mailto` schemes and adds a decisionHandler for `mailto` schemes on `WebViewController`. If the device cannot send mail, an alert is displayed.

NetNewsWire.xcodeproj/project.pbxproj

@@ -674,6 +674,9 @@
 		D5F4EDB720074D6500B9E363 /* WebFeed+Scriptability.swift in Sources */ = {isa = PBXBuildFile; fileRef = D5F4EDB620074D6500B9E363 /* WebFeed+Scriptability.swift */; };
 		D5F4EDB920074D7C00B9E363 /* Folder+Scriptability.swift in Sources */ = {isa = PBXBuildFile; fileRef = D5F4EDB820074D7C00B9E363 /* Folder+Scriptability.swift */; };
 		DD82AB0A231003F6002269DF /* SharingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = DD82AB09231003F6002269DF /* SharingTests.swift */; };
+		DF41F3AE245EFCD7004EFB01 /* URL-Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = DF41F3AD245EFCD7004EFB01 /* URL-Extensions.swift */; };
+		DF41F3C8245EFD45004EFB01 /* URL-Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = DF41F3AD245EFCD7004EFB01 /* URL-Extensions.swift */; };
+		DF41F3C9245EFD46004EFB01 /* URL-Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = DF41F3AD245EFCD7004EFB01 /* URL-Extensions.swift */; };
 		FF3ABF13232599810074C542 /* ArticleSorterTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = FF3ABF09232599450074C542 /* ArticleSorterTests.swift */; };
 		FF3ABF1523259DDB0074C542 /* ArticleSorter.swift in Sources */ = {isa = PBXBuildFile; fileRef = FF3ABF1423259DDB0074C542 /* ArticleSorter.swift */; };
 		FF3ABF162325AF5D0074C542 /* ArticleSorter.swift in Sources */ = {isa = PBXBuildFile; fileRef = FF3ABF1423259DDB0074C542 /* ArticleSorter.swift */; };
@@ -1635,6 +1638,7 @@
 		D5F4EDB620074D6500B9E363 /* WebFeed+Scriptability.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "WebFeed+Scriptability.swift"; sourceTree = "<group>"; };
 		D5F4EDB820074D7C00B9E363 /* Folder+Scriptability.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Folder+Scriptability.swift"; sourceTree = "<group>"; };
 		DD82AB09231003F6002269DF /* SharingTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SharingTests.swift; sourceTree = "<group>"; };
+		DF41F3AD245EFCD7004EFB01 /* URL-Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "URL-Extensions.swift"; sourceTree = "<group>"; };
 		FF3ABF09232599450074C542 /* ArticleSorterTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ArticleSorterTests.swift; sourceTree = "<group>"; };
 		FF3ABF1423259DDB0074C542 /* ArticleSorter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ArticleSorter.swift; sourceTree = "<group>"; };
 		FFD43E372340F320009E5CA3 /* MarkAsReadAlertController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MarkAsReadAlertController.swift; sourceTree = "<group>"; };
@@ -2405,6 +2409,7 @@
 				51126DA3225FDE2F00722696 /* RSImage-Extensions.swift */,
 				516AE9DE2372269A007DEEAA /* IconImage.swift */,
 				B2B8075D239C49D300F191E0 /* RSImage-AppIcons.swift */,
+				DF41F3AD245EFCD7004EFB01 /* URL-Extensions.swift */,
 			);
 			path = Extensions;
 			sourceTree = "<group>";
@@ -3852,6 +3857,7 @@
 				65ED401C235DEF6C0081F399 /* FaviconGenerator.swift in Sources */,
 				65ED401D235DEF6C0081F399 /* RefreshInterval.swift in Sources */,
 				65ED401E235DEF6C0081F399 /* TimelineCellData.swift in Sources */,
+				DF41F3C9245EFD46004EFB01 /* URL-Extensions.swift in Sources */,
 				65ED401F235DEF6C0081F399 /* BuiltinSmartFeedInspectorViewController.swift in Sources */,
 				65ED4020235DEF6C0081F399 /* AppDelegate+Scriptability.swift in Sources */,
 				65ED4021235DEF6C0081F399 /* NNW3Document.swift in Sources */,
@@ -4038,6 +4044,7 @@
 				51C4529F22650A1900C03939 /* AuthorAvatarDownloader.swift in Sources */,
 				5108F6D22375EED2001ABC45 /* TimelineCustomizerViewController.swift in Sources */,
 				519E743D22C663F900A78E47 /* SceneDelegate.swift in Sources */,
+				DF41F3C8245EFD45004EFB01 /* URL-Extensions.swift in Sources */,
 				FFD43E412340F488009E5CA3 /* MarkAsReadAlertController.swift in Sources */,
 				51C452A322650A1E00C03939 /* HTMLMetadataDownloader.swift in Sources */,
 				51C4528D2265095F00C03939 /* AddFolderViewController.swift in Sources */,
@@ -4156,6 +4163,7 @@
 				51EF0F922279CA620050506E /* AccountsAddTableCellView.swift in Sources */,
 				849A97431ED9EAA9007D329B /* AddFolderWindowController.swift in Sources */,
 				8405DDA522168C62008CE1BF /* TimelineContainerViewController.swift in Sources */,
+				DF41F3AE245EFCD7004EFB01 /* URL-Extensions.swift in Sources */,
 				844B5B671FEA18E300C7C76A /* MainWIndowKeyboardHandler.swift in Sources */,
 				848D578E21543519005FFAD5 /* PasteboardWebFeed.swift in Sources */,
 				5144EA2F2279FAB600D19003 /* AccountsDetailViewController.swift in Sources */,

Shared/Extensions/URL-Extensions.swift

@@ -0,0 +1,17 @@
+//
+//  URL-Extensions.swift
+//  NetNewsWire
+//
+//  Created by Stuart Breckenridge on 03/05/2020.
+//  Copyright © 2020 Ranchero Software. All rights reserved.
+//
+
+import Foundation
+
+extension URL {
+	
+	/// Extracts email address from a `URL` with a `mailto` scheme, otherwise `nil`.
+	var emailAddress: String? {
+		scheme == "mailto" ? URLComponents(url: self, resolvingAgainstBaseURL: false)?.path : nil
+	}
+}

iOS/Article/WebViewController.swift

@@ -12,6 +12,7 @@ import RSCore
 import Account
 import Articles
 import SafariServices
+import MessageUI
 
 protocol WebViewControllerDelegate: class {
 	func webViewController(_: WebViewController, articleExtractorButtonStateDidUpdate: ArticleExtractorButtonState)
@@ -310,6 +311,23 @@ extension WebViewController: WKNavigationDelegate {
 					let vc = SFSafariViewController(url: url)
 					self.present(vc, animated: true)
 				}
+			} else if components?.scheme == "mailto" {
+				decisionHandler(.cancel)
+				
+				guard let emailAddress = components?.url?.emailAddress else {
+					return
+				}
+				
+				if MFMailComposeViewController.canSendMail() {
+					let mailComposeViewController = MFMailComposeViewController()
+					mailComposeViewController.setToRecipients([emailAddress])
+					mailComposeViewController.mailComposeDelegate = self
+					self.present(mailComposeViewController, animated: true, completion: {})
+				} else {
+					let alert = UIAlertController(title: "Error", message: "This device cannot send emails.", preferredStyle: .alert)
+					alert.addAction(.init(title: "Dismiss", style: .cancel, handler: nil))
+					self.present(alert, animated: true, completion: nil)
+				}
 			} else {
 				decisionHandler(.allow)
 			}
@@ -666,3 +684,10 @@ private extension WebViewController {
 	}
 	
 }
+
+// MARK: MFMailComposeViewControllerDelegate
+extension WebViewController: MFMailComposeViewControllerDelegate {
+	func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
+		self.dismiss(animated: true, completion: nil)
+	}
+}