EXC_BAD_ACCESS on attempting access private CCLabelBMFont member within performselector

Question

I started a non ARC cocos2d project.

It throws error EXC_BAD_ACCESS while attempting to access private CCLabelBMFont member within performSelector:withObject:afterDelay:
title is allocating in doSomeInit method. But somehow I can't access it in doSomething method.
What should I do to access its children?
I put a simple example below:

a.h

@interface IntroLayer : CCLayer {

}
@property (nonatomic,strong) CCLabelBMFont *_title;
@end

also tried this... no luck. a.h

@interface IntroLayer : CCLayer {
   CCLabelBMFont *_title;
}

---

a.m

@implementation IntroLayer
@synthesize _title;
 .
 .
- (void)doSomeInit {
    _title = [CCLabelBMFont labelWithString:@"Test Label" fntFile:"blah.fnt"];
    [self performSelector:@selector(doSomething) withObject:nil afterDelay:5];
}

- (void)doSomething {
    int count = 0;
    for (CCSprite* la in _title.children) { //<<<<<EXC_BAD_ACCESS ERROR THROWS HERE!!!
        la.opacity = 0;
    }
    [self addChild: _title];
}

---

Next relevant Question is this:
I modified
_title = [CCLabelBMFont labelWithString:@"Test Label" fntFile:"blah.fnt"];

to

_title=[CCLabelBMFont labelWithString:@"Test Label" fntFile:"blah.fnt"];  
[_title retain]; //this fixes EXC_BAD_ACCESS error. 

But:
Question 2: Is retain method leaking any memory?
Maybe I should release it in overidden -(void)onExit method?

Answer 1

In your method doSomeInit, your statement _title = [CCLabelBMFont labelWithString:@"Test Label" fntFile:"blah.fnt"]; assigns an autorelease CCLabelBMFont object to _title directly, i.e. without using the setter method. Therefore, this object is not retained, and released as soon as the app returns to the main run loop. So when doSomething executes, this object is released, and you get the EXC_BAD_ACCESS error.
You should use the setter method self._title = [CCLabelBMFont labelWithString:@"Test Label" fntFile:"blah.fnt"];