Demo of Fast App Switching apps on iOS 4
[Apple calls this "fast app switching", but I called it state saving in the vid -- oops]
Patrick mentioned earlier that the first wave of iOS 4 compatibility updates have arrived, but I thought I’d try and show exactly what you can look forward to when the final version of the OS is released this Monday. Please note that this behaviour should not be expected by default. Default iPhone apps like Photos, Settings, and Calendar already support state saving, but we’ll have to wait for specific iOS 4 compatibility updates before other apps save their states. Pastebot and Evernote have already been updated, though.
It should also be noted that there are other forms of iOS 4 multitasking coming soon, but they don’t seem to work properly on the iOS 4 GM (final beta) I have installed. Evernote can now initiate background uploads and downloads, as well as record audio notes in the background, but I don’t see any of the indicators (flashing red bar) that are shown on this Evernote blog post. I’m guessing we’ll have to wait until Monday to see everything the way it should be.
Say if you had 2 apps running, (ie. evernote and calendar), would it consume double the battery power? Or when an app gets switched to the background, does it go into a sort-of "sleep" mode where it consumes less power? This is my number one concern/question with OS 4. If it consumes the same amount of battery, I might as well just close an app before switching and save myself the hassle of charging my iPhone even more than I already do. I haven't read anything about this, and I'm very curious! Great vid Thomas!
Thanks Jordan
Fast app switching is a lot like the state saving that's already present in certain apps. The difference is that Apple basically added a switch to toggle this behaviour on developer side (I think default setting is on, according to Marco Arment's blog). This means it's much easier for devs to implement — or should be (I'm no dev).
However, what I do know is that it uses up no more battery than before. These apps aren't actually running in the background, unless they're actively uploading or downloading. They just save exactly where they were so that reloading is so fast it *feels* like multi-tasking.
This is different from actual tasks that can now run in the background, like uploading or downloading, background audio, etc.
Thanks for such a thorough answer. That's actually what I was hoping for cause lord knows I already have to charge my iphone way too much! For my uses, I don't need to be switching between apps very much, but knowing that it won't eat up my battery excessively lets me know I'll be okay with upgrading. Thanks again.
Oops — revise my last comment. There is no such thing as background updating. I meant to say that they can finish uploading a file in the background (if an app updates with that API), but there is now background downloading of info. Only stuff like IM's from Beejive, etc. do this, and that's through push notifications.