If you are looking at doing Timelapse I would certainly recommend the iTimeLapse iPhone App. (Note, you need a camera on your device so the old iPod Touch cannot use this app)
The iTimelapse iPhone App allows you to create a timelapse project, specifying the timelapse interval, duration of the project, & size of the video. During rendering you can output at varying framerates, add music and add a filename. The timelapse videos can then be output to your camera roll / library for sharing.
The quality of the videos are very good and I feel I could be getting slowly addicted to timelapseing … But it is enjoyable especially if you have a nice subject, e.g. sunset, cityscape, or something which is slow moving but interesting to watch over time.
I would recommend that you switch to Airplane Mode, turn off sound, turn down the brightness, and if you are running a timelapse which takes mire than 2 hours that you have a full battery or stay on AC power.
Your projects in iTimeLapse are saved so if you render & export your video at 12fps and you find that it is too jumpy then you can re-render later by accessing the project file and changing the fps of the timelapse.
Have a look at a sample which I created this month in Sydney, Australia.
The iTimeLapse iPhone app is available in the app store at €2.99 – well worth it, a nice fun app.
There is an inbuilt timelapse function now added to the iPhone in subsequent years and I often just use that now, the only advantage to using a proper app for timelapse is that you can set the interval. On the iPhone version, you have to run with the interval set on the phone, but maybe you want once a minute or once every 10 minutes, using a dedicated timelapse app is the best way to get the result you want and the best way to ensure that you have a good final timelapse. Remember to plug your phone into a power supply or power bar as these apps do drain the battery quite a bit over the time required.