Which type of storage between HDD and SSD should I use in MacBook Pro for app development job?
It depends on your project size, but an SSD is unlikely to make a huge difference in compilation speeds - it's almost entirely a CPU-bound task. However an SSD can still make a big difference in your productivity with Xcode, and OS X in general. It particularly helps when you're indexing files in a project, or searching the documentation.

You'll also notice a big improvement whenever you're swapping to disk (e.g. if you're doing another task while a big compile is happening).

Unless money is very tight, I strongly recommend getting an SSD. You can save a lot of money buying a 3rd party SSD and installing it yourself (which is pretty easy in a MacBook Pro) - prices have been dropping sharply lately, I'd estimate about 50% from where they were at the start of the year.