You can use vacuum cleaner, but make sure your laptop's keyboard doesn't have "pop off" keys that could possibly be sucked up by the vacuum.

A can of compressed air will safely blow dust right out of the little crevices between your keys.

You may want to read this article from LifeHacker.

Is it okay to vacuum a laptop keyboard?
Not long ago I started learning Objective-C with an interest of developing apps. I have just started my first app and I have no clue how to make my app retina. I made the design in photoshop and exported it as a png @ 2,048 x 1,536 but however the size of my storyboard is only 1,024 x 768. I have read somewhere on the internet that you need two story boards but I am not sure how to link everything together. I would really appreciate it if someone could help me.
