I am unable to understand your question, In the presentation I have just outlined how I learnt Photoshop to design elements in our mobile app.

I'm just saying that, if you're a developer, isn't it better to directly code and ship an "almost okay" app in 1/2 week, get feedback and iterate than learning photoshop, wireframe, design, code and ship in 7/8 weeks?

In any case we had to get a design guy, even novice guys cost bomb, So I thought it was better spend a few weeks and learn.

I understand that. But which one is better : 8 weeks to learn how to play with photoshop, or 8 weeks to learn about your market and users?

If you end up with an app that is marketable and users will respect, the 8 weeks is probably worth it.

Besides, it's a skill that keeps giving. Now he cans spend the next week both writing and designing his next app instead of getting stuck with an ugly app and no designer.

Not sure i follow your point.

This guys are better than me to explain things probably : http://www.codinghorror.com/blog/2009/12/version-1-sucks-but... and http://successfulsoftware.net/2007/08/07/if-you-arent-embarr...

But I get all you points guys, no problem, and I find amazing that he managed to do all of that by himself.

This is what I do now. I used to go the full Photoshop mockup route, but now I find it more efficient to just start coding.

Yep, Jason Fried released a blog article about that few years ago. High Definition prototypes.