Expanding upon the Lock Screen Grabber (mockup)
It's all about the apps
To put iOS simply, it is entirely about getting from point A to B. Point A being wherever you are (say, the lock screen), and point B being the app you want to use. That is why the home screen is as simple as it is, in being a grid of apps. Once you understand this UX philosophy that the OS always tries uphold to, you can begin to see why something like widgets don't fit into Apple's 'motto' of simplicity.
More to the point, there are 'shortcuts' in iOS that allow you to jump into an app without going through the intermediary that is the home screen (aka springboard). These are things like notification center, as well as (to get back to the topic at hand), the:
Lock Screen Grabber
The lock screen camera grabber was born out of acknowledging a simple inconvenience in iOS; by the time you slide to unlock, perhaps enter a passcode, possibly exit the app you had running, then navigate the home screen to locate and launch the camera app, and then take a picture, it most likely would have been too late.
In other words; navigating to a very specific task you want to accomplish, such as taking a photo, was too slow on iOS. The camera grabber served as the perfect solution to this issue; quick access from the very first screen you encounter.
By placing a camera shortcut on your lock screen, the OS assumes that all of its users prioritize the camera function in an urgent situation, over other core functions. What about the phone? In a pinch, (or more dramatically, a life-or-death emergency), why is it easier for me to take a photo, than it is to access the very core function of the iPhone: the Phone. Or perhaps the iPod (which lest we forget, is a device for music).
The idea is simple; give the user a choice of instant access to core OS functions, without making them inherently choose one app (say, phone) over another (say, camera).
This is also hidden in a sense, as it doesn't affect or impede the current function we're all used to. Just swipe up on the camera grabber to get to the camera.
However, you'll notice if you didn't swipe up immediately, but rather place a finger on the camera grabber without lifting, additional shortcuts will make themselves visible. Since at this point the OS is aware that your intent is to use the grabber function, the slide to unlock mechanism can disappear momentarily as your finger is held, and thus make space for the extra shortcuts.
Note: just like passbook, Siri, and reply-with-message, there would be passcode options to disable lock screen access to your contacts, phone, texting, or all of the above, via the settings (currently under general>passcode lock).
This was something I came up with today while thinking of how to extend the great 'quick access' capabilities that the camera offers, while not re-thinking the entire UX of the lock screen function.
Anyhow, check my profile for my previously posted concept threads if you're interested. Until next time,
Thanks, and enjoy!