Q: I’m searching for a high-grade PDF framework which offers the possibility of creating pdfs on an iPad without internet connectivity. Can “PDFTron Mobile PDF SDK™” do this job? If yes, where can I buy it?
A: Yes, PDFTron Mobile PDF SDK for iOS (http://www.pdftron.com/pdfnet/mobile/ios_pdf_library.html) and Android can also be used to create and edit existing PDF files. As a starting point you may want to take a look at Objective C version of ElementBuilder sample: http://www.pdftron.com/pdfnet/samplecode.html#ElementBuilder
The SDK can be used to edit existing PDF files (see ElementEdit, PDFRedact, PDFPage, etc - see corresponding sample) and also includes a high-quality viewer which outperforms iOS/Mac Preview which lacks support many PDF features and chokes on certain files.