Diagram App for iOS

Dear developers, I need to create a Diagram iPad App similar to "Idea Sketch": [login to view URL] You can download the lite version for free. I really like how it works, how it saves the information in *.xml files and its system of 'tags' to classify the created ideas (to know how it works you should export a file with their .sketch extension and then open the file in notepad, you'll see that it's an xml file indeed). I also like that in the paid version you can export the diagram created and it can be edited with another vector programs. So I want the App to have these features. I can make all the graphic design, you don't need to create it. I just need an App that does functionally what Idea Sketch does.