closing multitasking apps necessary?

It is not a multi-tasking dock it is a fast task switching dock.

Those programs are not in memory. Any background APIs will be denoted on the top of the screen.

 

Yeah. For example: An app like Skype, which can now run audio calls in the background, will have a little bar at the top of the screen just like when you go back to the home screen in the middle of a phone call.

 

I don't think this is completely true - I stressed the phone a bit by running about 60 apps in that "multitask list", and out of those, about half of them had processes running when I checked iStat. Definitely ALL of the iPhone-native apps had background processes, and I guess also the ones which NEED to be running in the background, such as Skype or LogMeIn (as I was connected to my Mac at the time.)

This isn't including the usual background apps required for the iPhone to operate, such as the Springboard and various daemons that have to run when the phone boots.

Here's the screenshot I took at the time, showing the apps that had background processes going. Other than iStat and LogMeIn, I just ran the apps, and then went back to the home screen to launch more.

The results were actually pretty good though - the phone definitely got a bit warm, but never got hot, and even running all of that, I still had 95 megs of RAM free, out of the available 512. The phone stayed very responsive, so I wouldn't worry too much about keeping a few extra apps open.

 

native apps run in the backround, even before IOS4.
Unless its Mail thats not closed, i dont think it effects battery life.
Mail keeps refreshing if left opened.

 

This is compltley untrue. Barely any applications have some type of mark when running in the background.

However, yes, that is a fast app switcher meaning that only applications that have the support for background API's will actually run on th background. According to Apple, you don't have to close anything in the switcher.

 

I have one of the new free flashlight apps that uses the camera's LED. It stopped working when I'd bring it up, either through the switching or from the springboard. The only way to get it working again was to remove it from the fast switching.

 

When did Skype update to allow background calling?

 

i had to close some gps apps manually. the location services arrow was still on top after pushing home

 

Every app you open will appear in the dock. It's just a history list.
Apps in that list can be in three different states:

1) Completely dead and unloaded. These apps are not in memory. They have quit - but they remain in the bar. Pressing the icon will relaunch the app - exactly like selecting it from the main icon screen.

2) In memory but not running. Modern compiled-for-iOS4 apps will remain in memory - and stay there until iOS4 boots them out. Pressing the icon will launch them and they will wake, carrying on from where they left-off with their state information preserved. Incidentally, selecting the icon from the main icon screen resumes them in exactly the same way.

Such apps don't place any demand on your resources. No impact on battery life. There's no point in cleaning up. iOS will tidy up automatically.

3) In memory but running in background. A handful of special case applications can run to a greater or lesser extent in the background. GPS navigation apps run all the time for example. It will be obvious which apps are doing this. Nav Apps, Streaming Audio etc.
These apps do use some resources, and in these instance you may want to explicitly stop the application.

C.