There are only two semi-official textbooks are out there for the IB Computer Science 2014 syllabus and no officially supported/recommended IBO Computer Science textbooks. They are good resources, but perhaps a bit too technical for mid-range students and go into more depth than the curriculum explicitly requires.

Core Computer Science (that deals with the core syllabus, both SL and HL)

Advanced Computer Science (that deals with the extra sections for the HL syllabus)