Image Source: Gizmodo iOS 4 has introduced a greater level of multitasking on the iPhone (3GS and 4) “ but it has not given us full-on multitasking as we see on desktop PCs, which is just not feasible on a smartphone yet. This is one of the biggest and most eagerly awaited new features in […]
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iOS 4 Multitasking – A Question & A Wish List Item

Jun 29th 2010 by

iOS4MulitaskingServices

Image Source: Gizmodo

iOS 4 has introduced a greater level of multitasking on the iPhone (3GS and 4) “ but it has not given us full-on multitasking as we see on desktop PCs, which is just not feasible on a smartphone yet.

This is one of the biggest and most eagerly awaited new features in iOS 4 and for the new iPhone 4.  I ‘m as happy as anyone about this new functionality, but I also have a question about it and a big wish list item related to it.

My Understanding of iOS 4 and Multitasking

If my understanding is correct, what we ‘ve really got with iOS 4 is a tightly defined and limited amount of added genuine multitasking “ for very specifically defined services within certain apps (as shown in the screencap above) and a fairly elegant and simple execution of rapid app switching for all apps that are updated to take advantage of it.

So what we see when we open the iPhone ‘s Multitasking Bar is really a list of recently used apps, not necessarily all apps that are currently running in the background.  The vast majority of apps (those that are not using one of the allowed services that truly run as a background thread/process) are in a ‘suspended ‘ or paused state, with their exact state remembered from when you last left them if they have been updated for iOS 4. 

That ‘s my understanding thus far of things “ please correct me in the comments if you have better knowledge on this.  Here is Gizmodo ‘s description of things from back when iOS 4 was first announced:

Apple claims their multitasking will save battery life and resources, unlike the competition. But how?

The reason is simple: This is not 100% true multitasking. Not in the sense that developers define it: All system resources are available to all applications, with the system assuming the role of a traffic controller, giving preference to some tasks and less preference to others as needed.

Free-for-all multitasking will consume way too many resources, especially memory. This will make the system choke, given the limited memory available in these devices. The CPU would also be taxed, and it would deplete the battery life quicker while slowing down applications running on the foreground.

Apple’s method, however, is quite clever: Basically, it allows you to pause applications ”like you can pause them in any UNIX-based operating system, while enabling some special services to allow some types of tasks ”like receiving calls or playing music ”to run on the background. There are seven kinds of services, and Apple says these will give the user the kind of multitasking they demand, but without choking the system

My Question

A lot of users of iOS 4 have concerns about battery drain with the new ‘multitasking ‘ features.  It is worrying for many to see that the Multitasking Bar shows so many apps in it. 

I would expect to see a hit on battery life and program memory (RAM “ not storage memory) when using an app like Pandora and letting music play in the background, or any other app that runs one of the allowed background services shown in the screenshot at the top of the post.  My question is what level of resource hit is there from all other apps that have been launched since the last iPhone reboot? Or do ‘paused ‘ apps have zero impact on battery / memory used? (I just can ‘t see this being the case)

My Wish List Item

I think it would be great if  we could choose which apps take advantage of the new background-paused functionality on iOS 4.  I ‘d like it if we were asked as we are with Notifications “ asked just once to turn background suspension (or a nicer, shorter term) On and Off for each app.

There are a large number of apps that I use that I just don ‘t need to be suspended in the background, that I ‘m happy enough to see launched fresh when I go to them and I don ‘t need to rapidly switch to.  Being able to turn these on and off like notifications would mean I ‘d never have to bother manually closing down these apps via the multitasking bar.

What Do You Think?

What ‘s your take on all of this?  Would you like to be able to choose which apps are paused in the background?  Or do you feel that these paused apps really don ‘t have any great impact on resources?

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