For those of us who want to record our gaming exploits, demo an app for the wider world to see, or email a tutorial to mum and dad through the wonder of video, it's fortunate that recording screencasts is no longer the exclusive preserve of devs and serious coders. Whatever platform your smartphone (or tablet) runs, you can record on-screen activity without too much trouble.
Recording screencasts from iOS is pretty straightforward if you have a new-ish iPhone and Mac machine on hand (as you might expect, Apple makes life much easier if you use a lot of its gear). The version of QuickTime bundled with Yosemite (or later) can record activity on the screen of devices running iOS 8 (or later) without breaking a sweat.
To get started, plug your iDevice into your Mac OS X computer. Launch QuickTime, then choose New Movie Recording from the File menu. Click the drop-down menu next to the big record button and you should see your phone or tablet listed, assuming you've connected it to a trusted computer. With the right audio and video input selected, click the central button to start and stop recording. You can then save or export the clip as required.
Note that the time of your device is set to Apple's preferred 9:41am while you're recording — don't suddenly panic that someone has taken over your device, as it reverts back to normal once you hit the stop button. It's also worth remembering you have the option of using your computer's mic or the one on your iPhone if you want to add an audio narration to the video.
If you don't have a MacBook or iMac lying around then it gets a bit more complicated. Third-party apps just don't have enough device access to be able to record screencasts (unless you're in the mood to jailbreak), so you're going to need a computer of some description — unfortunately the QuickTime version of Windows doesn't have the same capabilities as the Mac one.
There's a decent selection of programs that can fill the gap but you'll have to pay to get them. X-Mirage is one option for Windows that you can pick up for $US16 ($22) — it works via AirPlay so the screen of your iPhone or iPad is beamed to your desktop wirelessly. Reflector 2 ($US14.99 ($20)) and AirServer ($US14.99 ($20)) work in the same way and are also worth a look.
Recording screencasts on Android has been made much easier with the release of the YouTube Gaming app (compatible with devices running Android 4.1 and above). Obviously it's designed primarily to record your gaming exploits, but you can use it to log pretty much anything you're doing on your device, no computer connection required.
Once you've installed the app, launch it and tap Go Live in the corner (depending on your device and its orientation the option may be hidden behind your avatar): You won't suddenly find yourself in front of an audience of millions but you will be able to record on-screen activity. Tap Next then choose your format and make sure Record is selected before tapping Next again twice.
The subsequent screen lets you choose an app to record — this will start the recording but you don't have to stay inside this app if you don't want to. Tap Start Now to begin and you're off: Down at the bottom of the screen is a console that lets you turn the microphone input on and off, and choose whether or not to include a live stream of your beautiful face as well (tag and drag to reposition this console). Select the stop button when you've finished.
You're then given the option to trim your video and upload it to YouTube (where you can set it as private) but if you'd rather not transfer it to the web then you don't have to — just back out of the screen and you'll find your video saved in your device's gallery, where you can edit and do whatever you want with it.
The YouTube Gaming app records everything on your screen, including notifications, so you might want to switch these off before you get started. It also includes the recording console. If you don't like this approach, there are plenty of alternatives you can check out: Try OneShot (free), Rec. (free with in-app purchases) or AZ Screen Recorder (free with in-app purchases) if you're after something different.