Ask HN: How long will it take to make an iPhone app w/ no experience?

I'm a programmer. I know Java, Python, Ruby on Rails, Javascript/CSS, but I have no experience developing iPhone apps. I know it uses Objective C, and Cocoa, but other than that, I don't know anything else.

Let's say I want to build an iPhone app that's fairly complex to use, such as an app that keeps track of spending and budgeting. Suppose I have 4 hours per day to work on this. How long do you think it will take me to complete the entire app (from learning Objective C, design, implementation, etc)?