I'd like to see Hard test data on that .... it uses no system resources, same as quitting, just stays on the dock ???! I call is BULLCHT!
If it uses
nosystem resources why they didn't include multitasking on older devices ?
And according to my OWN testing on 3gs... multitasking (leaving apps on the dock) does affect battery and performance... but since it's been only a few days, I am not going to speak early on that one just yet....
so.. my point, it takes 4 actions to "QUIT" an application properly ...
That's apple's way of multitasking.... and that's what I call cumbersome!
Thank you for listening .....
btw... most apps do just quit because they haven't been updated for multitasking yet....
There is a lot of misinformation in this thread, so I'll try to clear it up a little with some testing I did.
First, MOST apps ARE NOT running when they are in the "tray", we'll call it (the tray that pops up when you double tap home). Apps that remember where you left off, typically do just that, remember where you were, save their state to the STORAGE memory (not the RAM), and close completely.
Other apps DO stay running for varying amounts of time. Some apps stay "running" constantly to update, some stay running until you need the memory so that you can swap to them fast.
Here's how I obtained the information I use to make these conclusions. On my 3G, I had multitasking enabled, and was obviously jailbroken. I had SBSettings installed, so I could see the process list and compare it to the icons in the tray. The majority of icons in the tray were NOT running processes (granted a lot of apps are still not updated to utilize iOS 4), but some were. Pandora for example, obviously has to stay running to play music. Dropbox type apps stay running to sync. Flight Control was a good example of an app that stayed running so I could switch back fast, but it would have dropped itself if the memory was needed (I assume).
So yes, some apps stay running, some don't. Even if they are still "running", I believe they are coded so that just one small thread can keep running to do whatever it needs to do in the background, so memory, cpu, and battery usage is kept at an absolute minimum. Honestly, with the iPhone 4 I haven't closed an app from the tray yet, and never once have I noticed it slow down the slightest bit.
As usual, Apple has come late to the game, but has done it right. Apps will only run in the background if they need to, and only just to take care of what they have to do. Most apps just utilize features to remember where they were so that it seems like they stayed in the background the whole time even though they were actually closed.
Anyone who says this isn't "true" multitasking is a fool. You can only have one app on your screen at a time. There's no need for programs to be running and wasting resources if they aren't the app you're looking at at the moment. Apple provides some APIs for those apps that are the exception and actually have to do something in the background to minimize wasteful resource usage.
Edit: I just saw nenarek's link and it explains this very well. Think of most apps as closed state apps as the page mentions, where they are closed completely and save your session to your storage memory. Flight Control would be a suspended state app that stays in memory for fast switching, but basically use nothing but a little RAM until you go back to them. Pandora would be a background state app that stays running while in the background because it needs to keep doing something while it's not the active app. Dropbox and other syncing apps, I believe (but obviously I don't know their code so I can't say for sure), will drop to background state to finish whatever they need like syncing, then when they are finished drop further to suspended or even closed state.