A lot of fiction works have shown protagonists wearing in-sleeve pop-out launchers which hold some kind of weapon. The game Assassin’s Creed shows its Assassins hiding blades in their sleeves with which they launch stealth kills. Artemus Gordon from ‘The Wild Wild West’ TV show hides a single bullet pistol with that launcher in his arm for escapes. Intelligence officers have used it to hold derringers (a kind of pistol) to escape custody.
A Japanese man named Shota Mori has invented an iPhone holster with the same concept. No need to carry it around in your pocket and fiddle through your pockets to get it out to receive a call or read a text. After various failed attempts for his launcher, he finally perfected his design and now can apparently draw his iPhone while doing a ground roll. He has been working on it since 2011, during which his prototype faced ejection problems. The design was perfected in 2012 and can be used to quickly draw his iPhone from out of his hand.
In his demo video, Shota Mori, the inventor rolls on the ground and draws his iPhone to answer it as if he were in a gun battle. It seems pretty cool the way he does it.