I've always been fascinated by time lapse photography, where you capture a still image a few times a minute, then create a movie with a very speeded-up effect. The 1982 documentary film Koyaanisqatsi is really striking with its creative use of time lapse photography. Apple is adding a time lapse function to the Camera app in iOS 8, but if you'd like to play around with time lapse photography now try Time Lapse! for US$1.99.
Unlike the time lapse feature in iOS 8 -- at least what I've seen and used so far -- Time Lapse! lets you set the interval of exposures, from every 0.5 seconds for traffic and fast-moving weather, to 20 - 60 seconds for stars, growing plants or building construction. The app also features a real-time preview that works automatically while you are shooting so you can see what you have captured so far. The images are at full resolution, and your masterpiece is saved in Photos.
I tried the app out on a drive home, and the results were terrific. I put my iPhone on the dash, and secured it so it had a forward-facing view of my route. There is a tap to focus feature, but I just let the camera worry about it and my focus was fine. The app gives you the option to use your flash, but if you are running on battery power it's going to drain pretty fast.
From what I've seen to the iOS 8 implementation of time lapse photography, Time Lapse! is superior in every way. There's no flash support from Apple, and no way to adjust the exposure rate -- it's stuck at 10 second intervals.
My only Time Lapse! complaint is the start-stop control. The button is red when it is stopped and black when the time lapse is running, which seems backwards to me.
Other options include Time Lapse Camera (free but with ads), and Lapse It (free with a pro version for $2.00) has a good many features like screen dimming, white balance and some simple editing.
Time lapse is going to be big when it hits iOS. As usual, the Apple version is pretty simple and may suit most photographers, but other apps give you more flexibility and the chance at a better outcome. It's easy to use. Once you set up your exposure time it's just a click to get started and another click to stop.
Time Lapse! is a universal app and requires iOS 7 or later.