Revert "Remove usage of ! in call view."

This reverts commit 699bf0a829.

Signal/src/ViewControllers/CallViewController.swift

@@ -30,7 +30,7 @@ class CallViewController: OWSViewController, CallObserver, CallServiceObserver,
     // MARK: Views
 
     var hasConstraints = false
-    let blurView = UIVisualEffectView(effect: UIBlurEffect(style: .dark))
+    var blurView: UIVisualEffectView?
     var dateFormatter: DateFormatter?
 
     // MARK: Contact Views
@@ -43,7 +43,7 @@ class CallViewController: OWSViewController, CallObserver, CallServiceObserver,
 
     // MARK: Ongoing Call Controls
 
-    let ongoingCallView = UIView()
+    var ongoingCallView: UIView?
 
     var hangUpButton: UIButton?
     var audioSourceButton: UIButton?
@@ -58,7 +58,7 @@ class CallViewController: OWSViewController, CallObserver, CallServiceObserver,
 
     // MARK: Incoming Call Controls
 
-    let incomingCallView = UIView()
+    var incomingCallView: UIView?
 
     var acceptIncomingButton: UIButton?
     var declineIncomingButton: UIButton?
@@ -218,6 +218,9 @@ class CallViewController: OWSViewController, CallObserver, CallServiceObserver,
                                                                     action: #selector(didTouchRootView)))
 
         // Dark blurred background.
+        let blurEffect = UIBlurEffect(style: .dark)
+        let blurView = UIVisualEffectView(effect: blurEffect)
+        self.blurView = blurView
         blurView.isUserInteractionEnabled = false
         self.view.addSubview(blurView)
 
@@ -384,8 +387,7 @@ class CallViewController: OWSViewController, CallObserver, CallServiceObserver,
         setButtonSelectedImage(button: audioModeVideoButton, imageName: "audio-call-video-active")
         setButtonSelectedImage(button: videoModeVideoButton, imageName: "video-video-selected")
 
-        createContainerForCallControls(containerView: ongoingCallView,
-                                       controlGroups: [
+        ongoingCallView = createContainerForCallControls(controlGroups: [
             [audioModeMuteButton, audioSourceButton, audioModeVideoButton ],
             [videoModeMuteButton, hangUpButton, videoModeVideoButton ]
         ])
@@ -441,14 +443,13 @@ accessibilityLabel: NSLocalizedString("CALL_VIEW_DECLINE_INCOMING_CALL_LABEL",
                                                                      comment: "Accessibility label for declining incoming calls"))
         self.declineIncomingButton = declineIncomingButton
 
-        createContainerForCallControls(containerView: incomingCallView,
-                                       controlGroups: [
+        incomingCallView = createContainerForCallControls(controlGroups: [
             [acceptIncomingButton, declineIncomingButton ]
             ])
     }
 
-    func createContainerForCallControls(containerView: UIView,
-                                        controlGroups: [[UIView]]) {
+    func createContainerForCallControls(controlGroups: [[UIView]]) -> UIView {
+        let containerView = UIView()
         self.view.addSubview(containerView)
         var rows: [UIView] = []
         for controlGroup in controlGroups {
@@ -468,6 +469,7 @@ accessibilityLabel: NSLocalizedString("CALL_VIEW_DECLINE_INCOMING_CALL_LABEL",
         containerView.setContentHuggingVerticalHigh()
         rows.first?.autoPinEdge(toSuperviewEdge: .top)
         rows.last?.autoPinEdge(toSuperviewEdge: .bottom)
+        return containerView
     }
 
     func createButton(imageName: String, action: Selector, accessibilityLabel: String) -> UIButton {
@@ -536,6 +538,10 @@ accessibilityLabel: NSLocalizedString("CALL_VIEW_DECLINE_INCOMING_CALL_LABEL",
     // MARK: - Layout
 
     override func updateViewConstraints() {
+        guard let blurView = blurView else {
+            owsFail("\(TAG) missing blurView.")
+            return
+        }
         guard let localVideoView = localVideoView else {
             owsFail("\(TAG) missing localVideoView.")
             return
@@ -544,6 +550,14 @@ accessibilityLabel: NSLocalizedString("CALL_VIEW_DECLINE_INCOMING_CALL_LABEL",
             owsFail("\(TAG) missing remoteVideoView.")
             return
         }
+        guard let ongoingCallView = ongoingCallView else {
+            owsFail("\(TAG) missing ongoingCallView.")
+            return
+        }
+        guard let incomingCallView = incomingCallView else {
+            owsFail("\(TAG) missing incomingCallView.")
+            return
+        }
 
         if !hasConstraints {
             // We only want to create our constraints once.
@@ -748,7 +762,7 @@ accessibilityLabel: NSLocalizedString("CALL_VIEW_DECLINE_INCOMING_CALL_LABEL",
         if isShowingSettingsNag {
             settingsNagView.isHidden = false
             contactAvatarView.isHidden = true
-            ongoingCallView.isHidden = true
+            ongoingCallView?.isHidden = true
             return
         }
 
@@ -762,10 +776,10 @@ accessibilityLabel: NSLocalizedString("CALL_VIEW_DECLINE_INCOMING_CALL_LABEL",
 
         // Show Incoming vs. Ongoing call controls
         let isRinging = callState == .localRinging
-        incomingCallView.isHidden = !isRinging
-        incomingCallView.isUserInteractionEnabled = isRinging
-        ongoingCallView.isHidden = isRinging
-        ongoingCallView.isUserInteractionEnabled = !isRinging
+        incomingCallView?.isHidden = !isRinging
+        incomingCallView?.isUserInteractionEnabled = isRinging
+        ongoingCallView?.isHidden = isRinging
+        ongoingCallView?.isUserInteractionEnabled = !isRinging
 
         // Rework control state if remote video is available.
         let hasRemoteVideo = !remoteVideoView.isHidden
@@ -785,7 +799,7 @@ accessibilityLabel: NSLocalizedString("CALL_VIEW_DECLINE_INCOMING_CALL_LABEL",
         if shouldRemoteVideoControlsBeHidden && !remoteVideoView.isHidden {
             contactNameLabel.isHidden = true
             callStatusLabel.isHidden = true
-            ongoingCallView.isHidden = true
+            ongoingCallView?.isHidden = true
         } else {
             contactNameLabel.isHidden = false
             callStatusLabel.isHidden = false