Discussion for Tutorial 2 - Image Class

[mike]

Nice

[danegraphics]

I've found a not-so-major to major leak in the "getSubImageAtPoint" method. I've created an app that requires this method almost every frame and unless used so the leak is unnoticeable. The Leak Performance Tool traces it back to the first line:

Code: Select all

subImage = [[Image alloc] initWithTexture:texture scale:subImageScale];


It's clear that the allocated Image is never released and It's needs released after every frame without causing other problems (crashing, losing images in frame, etc.). How could that be done?

[mike]

I spotted some of these leaks when re-writing the methods for SLQ so the code in the book has been updated.

Fot this, I would set the returned image to autorelease e.g.

Code: Select all

return [subImage autorelease];


This will mean that where you are calling the method will have to do a retain on the returned subimage and then a release when its finished with it.

Let me know how you get on.

Cheers

Mike

[danegraphics]

Thanks that worked. No more Image leak. Thanks.

[Thorsten]

Hello Mike.

I have a memory problem with some of the classes I use from your tutorials. Instruments shows me, that I leak memory, when adding and removing images or spritesheets within my view. In these cases the methods from your classes are being called - i.e. getSpriteAtX:y:

I have the trackback from instruments here:

6 ColorRun -[SpriteSheet getSpriteAtX:y:] /Users/myUser/programming/colorrun_3.26/SpriteSheet.m:114
5 ColorRun -[Image getSubImageAtPoint:subImageWidth:subImageHeight:scale:] /Users/myUser/programming/colorrun_3.26/Image.m:183
4 CoreFoundation +[NSObject alloc]
3 CoreFoundation +[NSObject allocWithZone:]
2 libobjc.A.dylib _internal_class_createInstance
1 libobjc.A.dylib _internal_class_createInstanceFromZone
0 libSystem.B.dylib calloc


I'm pretty sure, that this is where the memory is leaked, but I do not know, whether the error is with me or in one of the classes I use from you. Within my code I allocate memory for new spritesheets and deallocate it again.

I was wondering whether you have any advice on how to approach this, since I have been trying to debug this without any success.

Thanks in advance!
Thorsten.

[mikewolf]

hi, there

the tutorial is very good. I like it, it is very helpful for me, as a new bee of iPhone game developer.

I have a question, should I write myself such class, e.g. Image Class and SpriteSheet Class and use them develop a game, or should I use cocos2d as game engine? In other words, those Tutorials are just for learning and for eventual understanding of the iPhone Game develop, then if man really want to develop a game, the cocos2d is a easy way?

Thanks again for the great job.

[A Person]

hi, there

the tutorial is very good. I like it, it is very helpful for me, as a new bee of iPhone game developer.

I have a question, should I write myself such class, e.g. Image Class and SpriteSheet Class and use them develop a game, or should I use cocos2d as game engine? In other words, those Tutorials are just for learning and for eventual understanding of the iPhone Game develop, then if man really want to develop a game, the cocos2d is a easy way?

Thanks again for the great job.

Well its really up to you, one thing that's nice about cocos2d is that everything is all setup working and ready to go with lots of features. However i find it hard to understand code that i haven't written even if its documented so that means if i need to do something special or change something i have a hard time. Besides you probably won't even use all the features cocos2d has, so for me i find that making my own engine with what i need it to do is the best way, i can change anything i want and i perfectly understand everything. If you don't find cocos2d hard to use and want to start creating iphone games right away and fast, then go with cocos2d.