Apply -> Never.

Signal/src/ViewControllers/AddContactShareToExistingContactViewController.swift

@@ -25,11 +25,11 @@ class AddContactShareToExistingContactViewController: ContactsPicker, ContactsPi
     }
 
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     @objc required public init(allowsMultipleSelection: Bool, subtitleCellType: SubtitleCellValue) {
-        fatalError("init(allowsMultipleSelection:subtitleCellType:) has not been implemented")
+        notImplemented()
     }
 
     // MARK: - ContactsPickerDelegate

Signal/src/ViewControllers/CallViewController.swift

@@ -136,7 +136,7 @@ class CallViewController: OWSViewController, CallObserver, CallServiceObserver,
 
     @available(*, unavailable, message: "use init(call:) constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("Unimplemented")
+        notImplemented()
     }
 
     required init(call: SignalCall) {

Signal/src/ViewControllers/ColorPickerViewController.swift

@@ -31,7 +31,7 @@ class ColorView: UIView {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 }
 
@@ -66,7 +66,7 @@ class ColorPickerViewController: UIViewController, UIPickerViewDelegate, UIPicke
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     override func loadView() {

Signal/src/ViewControllers/ContactViewController.swift

@@ -45,7 +45,7 @@ class ContactViewController: OWSViewController, ContactShareViewHelperDelegate {
 
     @available(*, unavailable, message: "use init(call:) constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("Unimplemented")
+        notImplemented()
     }
 
     @objc

Signal/src/ViewControllers/ContactsPicker.swift

@@ -87,7 +87,7 @@ public class ContactsPicker: OWSViewController, UITableViewDelegate, UITableView
     }
 
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     // MARK: - Lifecycle Methods

Signal/src/ViewControllers/ConversationView/ConversationHeaderView.swift

@@ -103,11 +103,11 @@ public class ConversationHeaderView: UIStackView {
     }
 
     required public init(coder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     required public override init(frame: CGRect) {
-        fatalError("init(frame:) has not been implemented")
+        notImplemented()
     }
 
     public override var intrinsicContentSize: CGSize {

Signal/src/ViewControllers/CropScaleImageViewController.swift

@@ -75,7 +75,7 @@ import SignalMessaging
 
     @available(*, unavailable, message:"use other constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     @objc required init(srcImage: UIImage, successCompletion : @escaping (UIImage) -> Void) {

Signal/src/ViewControllers/DebugUI/DebugUIFileBrowser.swift

@@ -21,7 +21,7 @@
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     override func viewDidLoad() {

Signal/src/ViewControllers/ExperienceUpgradesPageViewController.swift

@@ -418,7 +418,7 @@ private class ExperienceUpgradeViewController: OWSViewController {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     override func loadView() {
@@ -508,7 +508,7 @@ public class ExperienceUpgradesPageViewController: OWSViewController, UIPageView
     @available(*, unavailable, message:"unavailable, use initWithExperienceUpgrade instead")
     @objc
     public required init?(coder aDecoder: NSCoder) {
-        fatalError("unimplemented")
+        notImplemented()
     }
 
     // MARK: - View lifecycle

Signal/src/ViewControllers/GifPicker/GifPickerLayout.swift

@@ -21,7 +21,7 @@ class GifPickerLayout: UICollectionViewLayout {
 
     @available(*, unavailable, message:"use other constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     override init() {

Signal/src/ViewControllers/GifPicker/GifPickerViewController.swift

@@ -55,7 +55,7 @@ class GifPickerViewController: OWSViewController, UISearchBarDelegate, UICollect
 
     @available(*, unavailable, message:"use other constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     @objc

Signal/src/ViewControllers/HomeView/ConversationSearchViewController.swift

@@ -431,7 +431,7 @@ class EmptySearchResultCell: UITableViewCell {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     public func configure(searchText: String) {

Signal/src/ViewControllers/HomeView/MessageStatusView.swift

@@ -47,6 +47,6 @@ public class MessageStatusView: UIView {
     }
 
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 }

Signal/src/ViewControllers/LongTextViewController.swift

@@ -21,7 +21,7 @@ public class LongTextViewController: OWSViewController {
 
     @available(*, unavailable, message:"use other constructor instead.")
     public required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     @objc

Signal/src/ViewControllers/MediaGalleryViewController.swift

@@ -217,7 +217,7 @@ class MediaGalleryViewController: OWSNavigationController, MediaGalleryDataSourc
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     // HACK: Though we don't have an input accessory view, the VC we are presented above (ConversationVC) does.

Signal/src/ViewControllers/MediaPageViewController.swift

@@ -116,7 +116,7 @@ class MediaPageViewController: UIPageViewController, UIPageViewControllerDataSou
 
     @available(*, unavailable, message: "Unimplemented")
     required init?(coder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     deinit {

Signal/src/ViewControllers/MediaTileViewController.swift

@@ -65,7 +65,7 @@ public class MediaTileViewController: UICollectionViewController, MediaGalleryDa
     }
 
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     // MARK: View Lifecycle Overrides
@@ -791,7 +791,7 @@ private class MediaGallerySectionHeader: UICollectionReusableView {
 
     @available(*, unavailable, message: "Unimplemented")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     public func configure(title: String) {
@@ -824,7 +824,7 @@ private class MediaGalleryStaticHeader: UICollectionViewCell {
 
     @available(*, unavailable, message: "Unimplemented")
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     public func configure(title: String) {
@@ -917,7 +917,7 @@ private class MediaGalleryCell: UICollectionViewCell {
 
     @available(*, unavailable, message: "Unimplemented")
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     public func configure(item: MediaGalleryItem) {

Signal/src/ViewControllers/MenuActionsViewController.swift

@@ -52,7 +52,7 @@ class MenuActionsViewController: UIViewController, MenuActionSheetDelegate {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     // MARK: View LifeCycle
@@ -304,7 +304,7 @@ class MenuActionSheetView: UIView, MenuActionViewDelegate {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("not implemented")
+        notImplemented()
     }
 
     @objc
@@ -486,6 +486,6 @@ class MenuActionView: UIButton {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("not implemented")
+        notImplemented()
     }
 }

Signal/src/ViewControllers/MessageDetailViewController.swift

@@ -47,7 +47,7 @@ class MessageDetailViewController: OWSViewController, MediaGalleryDataSourceDele
 
     @available(*, unavailable, message:"use other constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     @objc

Signal/src/views/AttachmentPointerView.swift

@@ -75,7 +75,7 @@ class AttachmentPointerView: UIStackView {
 
     @available(*, unavailable, message: "use init(call:) constructor instead.")
     required init(coder aDecoder: NSCoder) {
-        fatalError("Unimplemented")
+        notImplemented()
     }
 
     private static var vSpacing: CGFloat = 5

Signal/src/views/AudioProgressView.swift

@@ -48,7 +48,7 @@ import SignalServiceKit
 
     @available(*, unavailable, message:"use other constructor instead.")
     @objc public required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     public required init() {

Signal/src/views/ContactCell.swift

@@ -50,7 +50,7 @@ class ContactCell: UITableViewCell {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     override func prepareForReuse() {

Signal/src/views/DismissableTextField.swift

@@ -30,7 +30,7 @@ class DismissInputBar: UIToolbar {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     @objc
@@ -55,7 +55,7 @@ public class DismissableTextField: UITextField, DismissInputBarDelegate {
     }
 
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     // MARK: DismissInputBarDelegate

Signal/src/views/GroupTableViewCell.swift

@@ -39,7 +39,7 @@ import SignalServiceKit
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     @objc

Signal/src/views/QuotedReplyPreview.swift

@@ -21,7 +21,7 @@ class QuotedReplyPreview: UIView {
 
     @objc
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     @objc

Signal/src/views/ReminderView.swift

@@ -32,12 +32,12 @@ class ReminderView: UIView {
 
     @available(*, unavailable, message:"use other constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     @available(*, unavailable, message:"use other constructor instead.")
     override init(frame: CGRect) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     private init(mode: ReminderViewMode,

Signal/src/views/Toast.swift

@@ -48,7 +48,7 @@ class ToastView: UIView {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     // MARK: Gestures
@@ -86,7 +86,7 @@ class ToastController: NSObject, ToastViewDelegate {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     // MARK: Public

SignalMessaging/ViewControllers/AttachmentApprovalViewController.swift

@@ -38,7 +38,7 @@ public class AttachmentApprovalViewController: OWSViewController, CaptioningTool
 
     @available(*, unavailable, message:"use attachment: constructor instead.")
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("unimplemented")
+        notImplemented()
     }
 
     @objc
@@ -494,7 +494,7 @@ class CaptioningToolbar: UIView, UITextViewDelegate {
     var textViewHeight: CGFloat
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     class MessageTextView: UITextView {

SignalMessaging/ViewControllers/ContactFieldView.swift

@@ -8,7 +8,7 @@ public class ContactFieldView: UIView {
 
     @available(*, unavailable, message: "use other constructor instead.")
     public required init?(coder aDecoder: NSCoder) {
-        fatalError("Unimplemented")
+        notImplemented()
     }
 
     public required init(rows: [UIView], hMargin: CGFloat) {

SignalMessaging/ViewControllers/ContactShareApprovalViewController.swift

@@ -159,7 +159,7 @@ class ContactShareFieldView: UIStackView {
 
     @available(*, unavailable, message: "use init(call:) constructor instead.")
     required init(coder aDecoder: NSCoder) {
-        fatalError("Unimplemented")
+        notImplemented()
     }
 
     required init(field: ContactShareField, previewViewBlock : @escaping (() -> UIView), delegate: ContactShareFieldViewDelegate) {
@@ -236,7 +236,7 @@ public class ContactShareApprovalViewController: OWSViewController, EditContactS
 
     @available(*, unavailable, message:"use other constructor instead.")
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("unimplemented")
+        notImplemented()
     }
 
     @objc

SignalMessaging/ViewControllers/EditContactShareNameViewController.swift

@@ -26,7 +26,7 @@ class ContactNameFieldView: UIView {
 
     @available(*, unavailable, message: "use other constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("Unimplemented")
+        notImplemented()
     }
 
     required init(name: String, value: String?, delegate: ContactNameFieldViewDelegate) {
@@ -136,7 +136,7 @@ public class EditContactShareNameViewController: OWSViewController, ContactNameF
 
     @available(*, unavailable, message:"use other constructor instead.")
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("unimplemented")
+        notImplemented()
     }
 
     @objc

SignalMessaging/ViewControllers/MediaMessageView.swift

@@ -56,7 +56,7 @@ public class MediaMessageView: UIView, OWSAudioPlayerDelegate {
 
     @available(*, unavailable, message:"use other constructor instead.")
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     // Currently we only use one mode (AttachmentApproval), so we could simplify this class, but it's kind

SignalMessaging/ViewControllers/MessageApprovalViewController.swift

@@ -28,7 +28,7 @@ public class MessageApprovalViewController: OWSViewController, UITextViewDelegat
 
     @available(*, unavailable, message:"use attachment: constructor instead.")
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("unimplemented")
+        notImplemented()
     }
 
     @objc

SignalMessaging/ViewControllers/ModalActivityIndicatorViewController.swift

@@ -26,7 +26,7 @@ public class ModalActivityIndicatorViewController: OWSViewController {
 
     @available(*, unavailable, message:"use other constructor instead.")
     public required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     public required init(canCancel: Bool) {

SignalMessaging/Views/AvatarImageView.swift

@@ -92,7 +92,7 @@ public class ConversationAvatarImageView: AvatarImageView {
     }
 
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     @objc func handleSignalAccountsChanged(notification: Notification) {

SignalMessaging/Views/DisappearingTimerConfigurationView.swift

@@ -49,7 +49,7 @@ public class DisappearingTimerConfigurationView: UIView {
     private var pressGesture: UILongPressGestureRecognizer!
 
     public required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     @objc

SignalMessaging/Views/GradientView.swift

@@ -14,7 +14,7 @@ public class GradientView: UIView {
     }
 
     public required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     public override func layoutSubviews() {

SignalMessaging/Views/OWSFlatButton.swift

@@ -34,7 +34,7 @@ public class OWSFlatButton: UIView {
 
     @available(*, unavailable, message:"use other constructor instead.")
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     private func createContent() {

SignalMessaging/Views/OWSNavigationBar.swift

@@ -35,7 +35,7 @@ public class OWSNavigationBar: UINavigationBar {
     }
 
     public required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     @objc

SignalMessaging/Views/TappableStackView.swift

@@ -12,7 +12,7 @@ public class TappableStackView: UIStackView {
 
     @available(*, unavailable, message: "use other constructor instead.")
     public required init(coder aDecoder: NSCoder) {
-        fatalError("Unimplemented")
+        notImplemented()
     }
 
     public required init(actionBlock : @escaping () -> Void) {

SignalMessaging/Views/TappableView.swift

@@ -11,7 +11,7 @@ public class TappableView: UIView {
 
     @available(*, unavailable, message: "use other constructor instead.")
     public required init?(coder aDecoder: NSCoder) {
-        fatalError("Unimplemented")
+        notImplemented()
     }
 
     public required init(actionBlock : @escaping () -> Void) {

SignalMessaging/Views/VideoPlayerView.swift

@@ -47,7 +47,7 @@ class TrackingSlider: UISlider {
     }
 
     required init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 }
 
@@ -98,7 +98,7 @@ public class PlayerProgressBar: UIView {
     }
 
     required public init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
+        notImplemented()
     }
 
     override public init(frame: CGRect) {

SignalServiceKit/src/Util/OWSSwiftUtils.swift

@@ -20,10 +20,8 @@ public func assertOnQueue(_ queue: DispatchQueue) {
 public func AssertIsOnMainThread(file: String = #file,
                                  function: String = #function,
                                  line: Int = #line) {
-    guard Thread.isMainThread else {
+    if !Thread.isMainThread {
-        let filename = (file as NSString).lastPathComponent
+        owsFail("Must be on main thread.", file: file, function: function, line: line)
-        owsFail("\(filename):\(line) in \(function): Must be on main thread.")
-        return
     }
 }
 
@@ -33,11 +31,10 @@ public func owsFail(_ logMessage: String,
                     file: String = #file,
                     function: String = #function,
                     line: Int = #line) {
-    // TODO: Format using owsFormatLogMessage() once it is merged.
+    Logger.error(logMessage, file: file, function: function, line: line)
-    let message = "\(file) \(function) \(line): \(logMessage)"
-    Logger.error(message)
     Logger.flush()
-    assertionFailure(message)
+    let formattedMessage = owsFormatLogMessage(logMessage, file: file, function: function, line: line)
+    assertionFailure(formattedMessage)
 }
 
 // Once we're on Swift4.2 we can mark this as inlineable
@@ -45,8 +42,17 @@ public func owsFail(_ logMessage: String,
 public func owsProdExit(_ logMessage: String,
                         file: String = #file,
                         function: String = #function,
-                        line: Int = #line) {
+                        line: Int = #line) -> Never {
 
     owsFail(logMessage, file: file, function: function, line: line)
-    fatalError(logMessage)
+    let formattedMessage = owsFormatLogMessage(logMessage, file: file, function: function, line: line)
+    fatalError(formattedMessage)
+}
+
+// Once we're on Swift4.2 we can mark this as inlineable
+// @inlinable
+public func notImplemented(file: String = #file,
+                           function: String = #function,
+                           line: Int = #line) -> Never {
+    owsProdExit("Method not implemented.", file: file, function: function, line: line)
 }

SignalShareExtension/SAEFailedViewController.swift

@@ -29,7 +29,7 @@ class SAEFailedViewController: UIViewController {
 
     @available(*, unavailable, message:"use other constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     override func loadView() {

SignalShareExtension/SAELoadViewController.swift

@@ -50,7 +50,7 @@ class SAELoadViewController: UIViewController {
 
     @available(*, unavailable, message:"use other constructor instead.")
     required init?(coder aDecoder: NSCoder) {
-        fatalError("\(#function) is unimplemented.")
+        notImplemented()
     }
 
     override func loadView() {