Fix UTI recognition

Screenshottr/GCPAuthHandler.swift

@@ -86,13 +86,8 @@ class GCPAuthHandler {
             print(path)
             let fileURL = URL(fileURLWithPath: path)
             // Use UTIKit to grab the first MIME type recorded.
-            let potentialMimeTypes = UTI(fileURL.pathExtension).mimeTypes
-            var mimeType : String
-            if (potentialMimeTypes == []) {
-                mimeType = "application/octet-stream"
-            } else {
-                mimeType = potentialMimeTypes[0]
-            }
+            let mimeType = UTI(filenameExtension: fileURL.pathExtension)?.mimeType ?? "application/octet-stream"
+        
             print(mimeType)
             let uploadParameters = GTLRUploadParameters.init(fileURL: fileURL, mimeType: mimeType)
             let newObject = GTLRStorage_Object()