Fix timelapse export breaking

SilicaViewer/AppDelegate.swift

@@ -270,10 +270,12 @@ class AppDelegate: NSObject, NSApplicationDelegate, NSUserInterfaceValidations {
                 mainComposition.frameDuration = CMTimeMake(value: 1, timescale: 30)
                 mainComposition.renderSize = CGSize(width: document!.info.videoFrame.0, height: document!.info.videoFrame.1)
                 
-                self.exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality)
+                self.exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetMediumQuality)
                 self.exporter?.outputURL = savePanel.url!
                 self.exporter?.videoComposition = mainComposition
                 
+                try? FileManager.default.removeItem(at: (self.exporter?.outputURL)!)
+                
                 switch(savePanel.allowedFileTypes![0]) {
                 case "mp4":
                     self.exporter?.outputFileType = .mp4;
@@ -291,18 +293,32 @@ class AppDelegate: NSObject, NSApplicationDelegate, NSUserInterfaceValidations {
                 let alert = NSAlert()
                 alert.messageText = "Exporting timelapse..."
                 alert.addButton(withTitle: "Cancel")
+                
+                let timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { timer in
+                    alert.messageText = String(format: "Exporting timelapse... %2.0f%%", self.exporter!.progress * 100.0)
+                }
+                
+                self.exporter?.exportAsynchronously {
+                    timer.invalidate()
+
+                    DispatchQueue.main.sync {
+                        if self.exporter?.status == .completed {
+                            alert.window.close()
+                        } else {
+                            if let errorMessage = self.exporter?.error?.localizedDescription {
+                                alert.messageText = errorMessage
+                            } else {
+                                alert.messageText = "An unknown error occurred."
+                            }
+                        }
+                    }
+                }
+                
                 alert.beginSheetModal(for: originalWindow) { (resonse) in
                     self.exporter?.cancelExport()
                     alert.window.close()
                 }
-                
-                self.exporter?.exportAsynchronously {
-                    if self.exporter?.status != .cancelled {
-                        DispatchQueue.main.sync {
-                            alert.window.close()
-                        }
-                    }
-                }
+
             }
         }
     }

SilicaViewer/Base.lproj/Main.storyboard

@@ -375,6 +375,9 @@ Dk51bWJlciBvZiBMYXllcnM
                                                 <imageView horizontalHuggingPriority="251" verticalHuggingPriority="251" translatesAutoresizingMaskIntoConstraints="NO" id="y0M-Hn-T88">
                                                     <rect key="frame" x="0.0" y="0.0" width="485" height="269"/>
                                                     <imageCell key="cell" refusesFirstResponder="YES" alignment="left" imageScaling="proportionallyDown" id="tHf-wP-P5i"/>
+                                                    <connections>
+                                                        <segue destination="qzy-T7-vHd" kind="show" identifier="showTimelapse" id="5t3-ps-pEB"/>
+                                                    </connections>
                                                 </imageView>
                                             </subviews>
                                             <constraints>
@@ -413,7 +416,7 @@ Dk51bWJlciBvZiBMYXllcnM
                 </viewController>
                 <customObject id="2Tp-Fl-jBw" userLabel="First Responder" customClass="NSResponder" sceneMemberID="firstResponder"/>
             </objects>
-            <point key="canvasLocation" x="132" y="725"/>
+            <point key="canvasLocation" x="89" y="697"/>
         </scene>
     </scenes>
 </document>

SilicaViewer/Document.swift

@@ -251,6 +251,10 @@ class Document: NSDocument {
     }
     
     func parseBasicObject(key: Any?) -> Any? {
+        if key == nil {
+            return nil
+        }
+        
         if let objectsArray = self.dict?["$objects"] as? NSArray {
             let classID = getClassID(id: key)