Sparrow Forum

1. 

   Oscar
   Member

   Hi all,

   I'm slowly progressing with my game thanks Sparrow. A couple of questions regarding memory managment have popped up though. Even though I've search around a lot on google I can't honestly say I understand it fully, though I think I've grasped the basic concepts.

   1. In a function such as this:

   -(id)initWithWidth:(float)width withHeight:(float)height atX:(float) atY:(float)y toObj:(Sprite*)targetObj inWorld:(b2World*)targetWorld

   Should I release the initvars such as x, width, toObj etc?

   2. I'm using an NSMutableSet to store my player animations such as this:

   playerAnimationsArray = [[NSMutableSet alloc] init];
   [playerAnimationsArray addObject:playerMC];
   [playerAnimationsArray addObject:playerIdleMC];
   [playerAnimationsArray addObject:playerJumpMC];
   [playerAnimationsArray addObject:playerPushingMC];

   After I've added these movieclips to the juggler on the main stage I tried to remove the array by doing [playerAnimationsArray release]; but if I do the game will crash. If I leave it out it runs fine. This is against the apparent rule that whenever you alloc something it will need to be released at some point. Can I just leave it be? I have a few other arrays that I can't seem to release either.

   3. If I do a simulated memory warning in the ios simulator my game will crash. I have no clue what would be causing this. I have a dealloc function in each class in my game that calls [super dealloc];.

   4. if I make properties in a class, should these be released? Also, how do I remove an entire object I've allocated the correct way?

   Posted 1 year ago #
2. 

   ronaldmathies
   Moderator

   1:

   Primitives (like int, BOOL, float, etc..) never need to be released (it's not possible).

   If you retain toObj inside the initWithWidth method then yes you need to release it in the dealloc of that object.

   Normally the rule of thumb is:

   The object that retains a value should release the value. So if you create an object and retain it in Class X and you pass it along in Class Y and Class Y also retains it then class Y should release it and class X also.

   2:

   Could it be that the objects inside your playerAnimationsArray have been released to often? Suppose i have the following:

   playerMC = [[[SomeClass alloc] init] autorelease];
    
   playerAnimationsArray = [[NSMutableSet alloc] init];
   [playerAnimationsArray addObject:playerMC];
    
   [playerMC release];

   Because this could be a reason why your code crashes.
   playerMC is released two times while it has only be retained two times.

   To explain a bit in detail:

   The alloc/init retains playerMC the first time.
   The [playerAnimationsArray addObject:playerMC] retains the playerMC a second time.

   But the autorelease releases the player the first time and the [playerMC release] releases the player a second time.

   So the playerMC that is inside the array has a retaincount of 0, if you release the array it could cause a problem.

   3. This could be caused for example by the arrays, if you cannot release the array yourself without crashing the mechanism for handling memory warnings could also try to release the array resulting in a crash (this would mean that in the memory warning handling you try to release the array).

   4. The first part i can't say without any example code, for the second part:

   Player *player = [[Player alloc] init]; // Creates a complete object.
   [player release]; releases the complete object.

   Every object that is retained inside the player should be released inside the dealloc of the player.

   Take a look at the classes of Sparrow like SPDisplayObject, they are quite clear on how to do this.

   Posted 1 year ago #
3. 

   Daniel
   Primary Feather

   2 more cents from me:

   In Ronalds sample in (2), be aware that it might be disguised like this:

   playerMC = [SomeClass someClass]; // <-- !!!
    
   playerAnimationsArray = [[NSMutableSet alloc] init];
   [playerAnimationsArray addObject:playerMC];
    
   [playerMC release];

   because the first line is a so called 'factory method' that is very common in ObjC. In the method, the class is alloc'ed, initialized and autoreleased, just as in Ronald's code.

   Furthermore, Xcode has a very interesting feature called "Build and Analyze", which is found in the 'Build' menu. It does a good job of finding at least the most basic memory management problems.

   Posted 1 year ago #
4. 

   Oscar
   Member

   Thanks a lot! Gave me a bit better understanding of the concept. I'll be sure to look into both the array issue and Build & Analyze.

   Posted 1 year ago #

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