If you're a iOS app developer, there will be a time where you actually need to record a screencast from your iOS device (namely iPhone, iPod Touch and the iPad). The traditional way to do this is either you use third-party applications on the device (read: need to be jailbroken), or a more standard direct-tv-out-into-video-capture-device method.
Now there is an easier way to do this - enter Reflector.app.
The idea is simple - turn any of your Macs into an AirPlay receiver, so that you can view your devices' screen directly on the Mac, and while at it - record it!.
First, configure your Reflector.app according to the device that you want to record. In this example I'm going to use the iPhone 5S:
Now, make sure your Mac and your device is within the same WiFi network. On the device, bring up the Control Center and you'll notice a new icon labeled 'AirPlay'
Tap on 'AirPlay' and you'll see something like this:
Pick your computer in the list, and turn on 'Mirroring'. Shortly you'll see your device's screen on the desktop:
To start recording, just press cmd+R or choose Device -> Start Recording. Press cmd+R or Device -> Stop Recording once you're done. It will export to a MOV (QuickTime) file that you can then import into iMovie or FinalCutPro for post-processing!
Here's a sample video:
Note: Notice there's no audio in the recording? That's because I got my iPhone's mute switch set to 'Mute' D-OH.
Hope this helps!