iOS (Jailbroken): There are a plenty of ways to get a camera shortcut on your iPhone, whether it's via the lock screen or otherwise, but Camera Grabber provides a method that's top notch. When your lock screen is visible, it provides a button you can tap and drag to slide the lock screen away and reveal the camera app underneath.
That's all there is to it. You just flick the lock screen away and your camera is ready and waiting to snap a quick photo. This is a free hack you can download from Cydia. Just search for "Camera Grabber", install it, and let Cydia restart SpringBoard. When it's done, you'll see the little camera swiping area to the right of your "Swipe to Unlock" switch. Just pull it upwards and you'll be good to go.
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