How could I know the exact reason behind Check In/Check Out failure?

Question

I am an iOS developer and implementing SharePoint integration in iPhone through one of my application. From the API information I got that there are 3 APIs related to Check In/Check Out/Undo Check Out functionality provided by SharePoint 2010.

But In the result information, I get only a boolean(true/false) for each operation. There are many conditions,

1. I try to check out a document which is already checked out by some other(since I am from my iPhone and is not synced with latest status of the site, how could I know the reason is "the file has already been checked out")

2. I try to check in a document which is not checked out by myself/as per my current status it is not checked out.(There may be 2 reasons for the "false" response, a)The file has been already checked out by some one else. b)The file has not been checked out by you). One way I could make an assumption is like, since I have not checked out the file I can not check in that. How can get the info if the condition is former one(a)?

These are the APIS given from SharePoint for the these functionalities,

URL : /_vti_bin/Lists.asmx

Check In : /_vti_bin/Lists.asmx?op=CheckInFile
SOAPAction: "http://schemas.microsoft.com/sharepoint/soap/CheckInFile"

Check Out : /_vti_bin/Lists.asmx?op=CheckOutFile SOAPAction: "http://schemas.microsoft.com/sharepoint/soap/CheckOutFile"

Undo Check Out : /_vti_bin/Lists.asmx?op=UndoCheckOut SOAPAction: "http://schemas.microsoft.com/sharepoint/soap/UndoCheckOut"

Please consider my question and give answers if possible.

Answer 1

I am not sure if I understand your question correctly.

Your iPhone MUST connect to SharePoint site to be able to perform any of these actions.

or

You can download the documents, work on them offline and check in the document once connected. Read more about SharePoint workspace to understand how this works.