need help to design solution

Dear All,

I need your help to find the best way to design my future iphone application.

The main purpose of my application is to retrieve 10 XML files every hours, and of course analyze XML content and display alert, or notifications. XML files are produced from Microsoft environment and from company network. Estimated users around 50.

My main concern is about the technology to choose to access to XML files.

I investigated the following solutions but I need your feedback to choose the best way to do it.

Solution 1: Use Drop Box
Microsoft Server send files to DropBox through sendtodropbox and my application can connect to DropBox to download files. This solution works but I am not sure about SendToDropbox stability and not confident about SendToDropbox SLA. Other concern, DropBox changed recently API and SDK…

Solution 2: Use OneDrive
Microsoft Server send files to OneDrive through outlook and my application can connect to OneDrive to download files. Main concern, I didn't find example to apply in Swift and it seems that I have to subscribe Microsoft dev license (process not clear for me)

Solution 3: Use Company Sharepoint
Microsoft Server send files to Sharepoint folder through company network and my application can connect to Sharepoint to download files. Main concern is clearly about security, my application need to know user and PWD to connect.

Solution 3: Use RSS Flow
Microsoft server push XML files as a RSS flow, my application has to work as a RSS reader. And user can subscribe easily.
Sounds the best solution but it seems that there is a big architecture to implement…

So, could you please to help me about the best design solution or maybe can you please suggest another way to investigate ?

Many Thanks
Sebastien