iOS

Solution: It was easy to check the file creation in real iOS device.After creation of file connect the device in your MAC.Goto window devices and simulators select the app that was listed and click the settings icon that shown below select the download content of the app. It will be exported the .xcuserdata that you had speeified to the path.Right click on the file select show package contents it will open a new finder window.Navigate to the documents folder and check that the specified file is created.

Solution: If you are created a directory or file in document directory then you can have . an option to check that it was created success or not. You have to log the path then goto xcode->Window->Organizer->document directory path then select the specified path that logged in your debug then check it was created or not.

Solution: When i tried to create a folder named "Inbox" in document directory it was not permitted.At the same time i try to create a folder named "inbox" it was works. I thing iOS did not allow to create a folder named Inbox...So try other names it works good. 

Solution: Yes sometimes it will happens.First you have to quit the xcode and check that xcode is closed if not then force close it. Restart the xcode and connect the new device.It will works good.