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What needs to be done to properly enter the background on iOS 4?
If I do nothing, I get the following error:
sgx error (background gpu access not permitted):
Program received signal: “SIGABRT”.
I added the following method, which gets called, but it's still crashing in swapBuffers
// for iOS 4
- (void)applicationDidEnterBackground:(UIApplication *)application
{
NSLog(@"did enter background");
[[CCDirector sharedDirector] pause];
}
I guess this has to be in future Cocos2D templates in files like
ccXXXAppDelegate.m
#ifdef __IPHONE_4_0
- (void)applicationWillEnterForeground:(UIApplication *)application
{
[[CCDirector sharedDirector] startAnimation];
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
[[CCDirector sharedDirector] stopAnimation];
}
#endifThis works great, but if anyone is still having trouble, remember to check that you aren't accidentally running multiple instances of the display link... I apparently had one too many calls to startAnimation and not enough stopAnimation calls to balance it out, so no matter how often i called stopAnimation, my director continued to run the main loop thanks to a detached instance of the display link ;-P
In any event, one should already be calling stopAnimation and startAnimation in their applicationDidBecomeActive: and applicationWillResignActive:, so I think most people will not even notice this issue.
I don't know why but if you call stopAnimation and startAnimation in your applicationDidBecomeActive: and applicationWillResignActive: you get this error "sgx error (background gpu access not permitted):"
This happens even if you call stopAnimation and startAnimation in your applicationDidEnterBackground and applicationWillEnterForeground:
What I did is use it like this, to stop the error:
- (void)applicationDidEnterBackground:(UIApplication *)application
{
[[CCDirector sharedDirector] stopAnimation];
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
[[CCDirector sharedDirector] startAnimation];
}
- (void)applicationWillResignActive:(UIApplication *)application
{
[[CCDirector sharedDirector] pause];
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
[[CCDirector sharedDirector] resume];
}This is how i did it:
To pause:
- (void) applicationDidEnterBackground:(UIApplication *)application
{
[[CCDirector sharedDirector] stopAnimation];
[[CCDirector sharedDirector] pause];
}
- (void)applicationWillResignActive:(UIApplication *)application
{
[[CCDirector sharedDirector] stopAnimation];
[[CCDirector sharedDirector] pause];
}When resuming:
- (void)applicationDidBecomeActive:(UIApplication *)application
{
[[CCDirector sharedDirector] stopAnimation]; // call this to make sure you don't start a second display link!
[[CCDirector sharedDirector] resume];
[[CCDirector sharedDirector] startAnimation];
}Someone else suggested a BOOL flag to make sure you don't call animation methods twice, but I find calling stopAnimation before startAnimation does the trick just as well...
An important thing to note is that applicationDidBecomeActive: is called also when you program starts for the first time, so if you call startAnimation there, without first stopping it, or checking for "first run", then you will have two display links running and no amount of stopAnimation will save your program from crashing when it is backgrounded...
you guys are great
Adamd
Member
jandrad's version works out better for me. I have a number of UIKit views and find that, although I stop animation before launching them, doing it zerien's way leaves me with with animation running when those views are up. You can tell right away because of the lag. So this is what worked ..
- (void)applicationDidEnterBackground:(UIApplication *)application
{
[[CCDirector sharedDirector] stopAnimation];
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
[[CCDirector sharedDirector] startAnimation];
}
- (void)applicationWillResignActive:(UIApplication *)application
{
[[CCDirector sharedDirector] pause];
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
[[CCDirector sharedDirector] resume];
}
Joethemonkey101
On probation
Joethemonkey101
On probation
Ok thanks
Zeraien,
Shouldn't you also add a resume in applicationWillEnterForeground with that code like this?
- (void)applicationWillEnterForeground:(UIApplication *)application
{
[[CCDirector sharedDirector] resume];
[[CCDirector sharedDirector] startAnimation];
}I would think your applicationDidEnterBackground might cause problems otherwise?
robodude666
Member
Hate to sound repetitive, but I recommend everyone who wants great App performance with Fast App Switching to checkout the following two WWDC2010 sessions:
Session 105 - Adopting Multitasking on iPhone OS, Part 1
Session 109 - Adopting Multitasking on iPhone OS, Part 2
Part 1 covers basic ideas of adopting multitasking, while Part 2 features the more specific applications like audio, location and task completion multitasking.
Like Apple mentions, in addition to stopping GPU usage you should also clear up as much memory. It might be a good idea to clear some caches, and do whatever else you can to decrease your app's memory footprint. The lower it is, the less of a chance the app has of being terminated.
Like Apple mentions, in addition to stopping GPU usage you should also clear up as much memory. It might be a good idea to clear some caches, and do whatever else you can to decrease your app's memory footprint. The lower it is, the less of a chance the app has of being terminated.
What about a call to [[CCTextureCache sharedTextureCache] removeUnusedTextures] in applicationDidEnterBackground:. Wouldn't that free up some memory?
robodude666
Member
That's the little bit that Cocos2D does to be a good Multitasking citizen. It will remove textures from cache that are no longer being used.
Depending on your game you may still be using all of the textures that you requested so it may end up not freeing much. Though, if you use a lot of textures for menus, etc. it will free up a bit for you.
In either case, you need to do YOUR share in trying to clean up after yourself. If you have your own caches, or other large amounts of allocated memory try freeing it if it's not too CPU expensive to reproduce.
You ultimately need to balance between using memory and using CPU. You don't want the game to take ages to resume, but at the same time you don't want your app to hold onto a lot of memory when it's in the background not being played.
I posted a little "poll" here about this: http://www.cocos2d-iphone.org/forum/topic/7567
Guys, I have added this code to my project. Am I right in saying that the multitask switching (sending cocos2d to background, then resuming it where it paused and left off) will only work if I compile for 4.0 or 4.1 and higher?
I have been developing with my Base SDK set to 3.2 and my iOS deployment target as 3.0 all along (so I can allow people still on version 3.0 and upwards to play the game). However, if I test in the iOS 4.1 simulator using a deployment target of iOS 3.0 or anything else other than 4.1, my game does not resume correctly - when switching back using the multitasking bar, it restarts the app. Only if I set my deployment target to 4.1 does this actually work - then my game is paused and resumed perfectly. Does this sound right to you, or am I doing anything wrong here? Here is my appdelegate code:
- (void)applicationWillEnterForeground:(UIApplication *)application
{
[[CCDirector sharedDirector] resume];
[[CCDirector sharedDirector] startAnimation];
}
- (void) applicationDidEnterBackground:(UIApplication *)application
{
[[CCDirector sharedDirector] stopAnimation];
[[CCDirector sharedDirector] pause];
}
- (void)applicationWillResignActive:(UIApplication *)application {
[[CCDirector sharedDirector] stopAnimation];
[[CCDirector sharedDirector] pause];
[OpenFeint applicationWillResignActive]; // Add for OpenFeint
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
[[CCDirector sharedDirector] stopAnimation]; // call this to make sure you don't start a second display link!
[[CCDirector sharedDirector] resume];
[[CCDirector sharedDirector] startAnimation];
[OpenFeint applicationDidBecomeActive]; // Add for OpenFeint
}@Shogan, two things. 1) Check that you don't have "UIApplicationExitsOnSuspend" in your Info.plist, and 2) that you have your Base SDK set to >=4.0. You should have the Base SDK set to >= 4.0 and the deploy target set to 3.0 or 3.13, and it should properly exit when running on non-multitasking iOS, and should background correctly when on a multitask-enabled iOS.
@sabshire, thanks for your help :) I don't have UIApplicationExitsOnSuspend in my plist, so thats a good start, in my Base SDK settings I have iOS Device 3.2 or iOS Device 4.1. No 4.0...
So I set to 4.1 as Base SDK and 3.0 as my deployment target and you were correct of course - I can now multitask in the simulator :) It suspends and resumes perfectly, even in the middle of game play. This is great, thanks again. I should have clicked that as multitasking was a new feature in 4.0 I should have needed Base SDK at 4.0 or higher!
Do Apple only accept new appstore submissions using iOS Device 4.0 or 4.1 at this point? Is it recommended to develop all new apps with this set to the highest setting and just use deployment targets if you want to support older iOS versions?
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