Memory Management on NSMutableArray - memory-leaks

Question

I read some materials about this then I tried to wrote a simple
app but got confused, here is the sample (using cocos2d template):
MySpriteObject class:
#import <Foundation/Foundation.h>
#import "cocos2d.h"
#interface MySpriteObject : CCNode {
CCSprite *mySprite;
NSString *spriteInfo;
}
#property(nonatomic,retain) CCSprite *mySprite;
#property(nonatomic,retain) NSString *spriteInfo;
#end
#import "MySpriteObject.h"
#implementation MySpriteObject
#synthesize mySprite;
#synthesize spriteInfo;
-(id) init
{
NSLog(#"MySpriteObject init");
if ((self = [super init])) {
self.mySprite = [CCSprite spriteWithFile:#"Icon.png"];
self.spriteInfo = [[[NSString alloc] initWithFormat:#"sprite info"] autorelease];
}
return (self);
}
-(void)dealloc
{
NSLog(#"MySpriteObject dealloc");
[self.spriteInfo release];
[super dealloc];
}
#end
MyObjectManager class:
#import "cocos2d.h"
#import "MySpriteObject.h"
#class MySpriteObject;
#interface MyObjectManager : CCNode {
}
+(MyObjectManager *)sharedMyObjectManager;
-(NSMutableArray *)func1;
-(NSMutableArray *)func2;
#end
#import "MyObjectManager.h"
#import "MySpriteObject.h"
#implementation MyObjectManager
static MyObjectManager *_sharedMyObjectManager = nil;
+(MyObjectManager *)sharedMyObjectManager
{
NSLog(#"MyObjectManager sharedMyObjectManager");
if (!_sharedMyObjectManager) {
if( [ [MyObjectManager class] isEqual:[self class]] )
_sharedMyObjectManager = [[MyObjectManager alloc] init];
else
_sharedMyObjectManager = [[self alloc] init];
}
return _sharedMyObjectManager;
}
-(id)init
{
NSLog(#"MyObjectManager init");
if( (self = [super init]) ) {
}
return self;
}
-(void)dealloc
{
NSLog(#"MyObjectManager dealloc");
[super dealloc];
}
-(NSMutableArray *)func1
{
NSMutableArray *array1 = [[NSMutableArray alloc] init];
array1 = [self func2];
return array1;
}
-(NSMutableArray *)func2;
{
NSMutableArray *array2 = [[NSMutableArray alloc] init];
for (int i = 0; i < 3; i++) {
MySpriteObject *mySpriteObject = [[MySpriteObject alloc] init];
[array2 addObject:mySpriteObject];
//[mySpriteObject release];
}
return array2;
}
#end
And in the "HelloWorldScene.m" init method:
-(id) init
{
if( (self=[super init] )) {
NSMutableArray *array = [[NSMutableArray alloc] init];
array = [[MyObjectManager sharedMyObjectManager] func1];
for (int i = 0; i < array.count; i++) {
MySpriteObject *s = [[MySpriteObject alloc] init];
s = [array objectAtIndex:i];
NSLog(#"%#", s.spriteInfo);
[s release];
}
[array release];
}
return self;
}
The code posted above works fine (at least no crash), but I think there is
memory leak out there.
At first, I had the fun1 fun2 method return the array like this:
return [array1 autorelease];
return [array2 autorelease];
And released the SpriteObject in the func2 methoed as you can see the commented line.
But the app crashed.
Then I uncommented the SpriteObject release line but it still crashed.
Then I deleted the two autorelease in the return statement and it worked
fine.
Can somebody give something suggestion according to the code above???
Thanks in advance.

Answer 1

Oh boy, there are multiple problems. At first remember to release everything you called "alloc, new, retain, copy" upon. See Objective C release, autorelease, and data types and Release, Dealloc, and the Self reference
The basic problem here is, that you are overwriting previously created variables. For example:
NSMutableArray *array = [[NSMutableArray alloc] init];
array = ... ;
[array release];
Therefore you create a memory leak and get double release trouble. See obj-c NSString and alloc / retain / release for how to do it right.