Strange error accessing a NSString from a delay

Strange error accessing a NSString from a delay_invocation

(6 posts) (2 voices)

Started 10 months ago by WhiteGollum
Latest reply from Daniel

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WhiteGollum
Member

Hi all,

I am stucked with one problem.

I have a function (lets call it sliceWord)that acces an NSString from his class, and with substringWithRange:NSMakeRange(X, 1) got a random letter from the string.

This function is called from a simple call: [self sliceWord:nil];
but at the end of SliceWord, I recall itself with this code: [[juggler delayInvocationAtTarget:self byTime:2.0f] sliceWord:nil];

The first iteration works great, but the second breaks in the function - (void)setCurrentTime:(double)currentTime of SPDelayInvocation.m

In a more precise way, it breaks in [mInvocations makeObjectsPerformSelector:@selector(invoke)];

No debug error, no more information.

I know the problem is with the acces to this NSString, because if I delete it the program works fine.

Any help really apreciated

Posted 10 months ago #
Daniel
Primary Feather

Hm ... the method "makeObjectsPerformSelector:" will call your "sliceWord" method internally, so I guess something in there will cause the crash. Can you perhaps post the code of that method?

Posted 10 months ago #

Thanks Daniel, I will try to explain the code (And sorry about my not very clear way of coding), consider that I am learning Objective C as I develop my little game

Here is the SliceWord:

- (void) sliceWord:(SPEvent *)event
{
    num_pieza++;
    Pieza *pieza;
    NSString *Letra;
 
    //This Works like a charm
    //Letra = [NSMutableString stringWithString: @"A"];
    //This do not work
    Letra = [mPalabra substringWithRange:NSMakeRange(0, 1)];
 
    pieza = [[Pieza alloc] initWithSpace:mSpace Image:@"cuadrado1-0.png"
        BX:mWidth-80 BY:5 BMass:1 Type:@"Rectangulo" SX:80  SY:80
        SElasticity:0.2f SFriction:100.0f SGroup:num_pieza
        CollisionType:@"Rectangulo" NivelAgua:mNivelAgua
        ParentSopaGame:(id *)self Text:Letra]; 
 
    [self addChild:pieza];
    [pieza.mBody setVelocity:cpv(-150+rand()%100, 0)];
 
    SPStage *stage = [SPStage mainStage];
    SPJuggler *juggler = [stage juggler];
    [[juggler   delayInvocationAtTarget:self byTime:2.0f] sliceWord:nil];
}

As you can see, in the sliceWord code, I assign "Letra" to a substring of a global variable, and then create an object "Pieza" with Text:Letra.

If I assing Letra a value of @"A", all works like a charm, but if I play with substrings all fails.

The estrange thing is that the first iteration works fine, and as soon as we go through the second iteration, the programs SIGFAULT.

Following your suggestions, maybe the error is on the "Pieza" Class code.
I attached the constructor initWithSace as follows:

- (id)initWithSpace: (CMSpace *)space Image:(NSString *)nombreImagen BX:(int)BX
    BY:(int)BY BMass:(float)BMass Type:(NSString *)Type SX:(int)SX SY:(int)SY
    SElasticity:(float)SElasticity SFriction:(float)SFriction SGroup:(int)SGroup
    CollisionType:(NSString *)collisionType NivelAgua:(int)nivelAgua
    ParentSopaGame:(id *)parentSopaGame
{
    if (self = [super init])
    {
        mParentSopaGame = parentSopaGame;
        bajo_agua = false;
        mNivelAgua = nivelAgua;
        mSpace = space;
 
        mImage = [SPImage imageWithContentsOfFile:nombreImagen];
        mImage.width = SX;
        mImage.height = SY;
	[mImage setX:-[mImage width] / 2.0f];
	[mImage setY:-[mImage height] / 2.0f];
	[self addChild:mImage];
 
        [self setX:BX];
        [self setY:BY];
 
        [self addEventListener:@selector(mueve_pieza:) atObject:self forType:SP_EVENT_TYPE_TOUCH];
	[self addEventListener:@selector(step:) atObject:self forType:SP_EVENT_TYPE_ENTER_FRAME];
 
	mBody = [mSpace addBodyWithMass:BMass moment:INFINITY];
        [mBody setPositionUsingVect:cpv(BX, BY)];
        [mBody addToSpace];
        [mBody setData:self];
        [mBody setVelocityFunction:self selector:@selector(velocityFunction:gravity:damping:dt:)];
	mShape = [mBody addRectangleWithWidth:SX height:SY];
	[mShape setElasticity:SElasticity];
	[mShape setFriction:SFriction];
	[mShape setGroup:(cpGroup)SGroup];
	[mShape setCollisionType:collisionType];
	[mShape addToSpace];
 
	mTouchBody = [[mSpace addBody] retain];
 
        //****** Text****
        TextField = [SPTextField textFieldWithWidth:SX height:SY text:texto];
        TextField.hAlign = SPHAlignCenter;
        TextField.vAlign = SPVAlignCenter;
        TextField.color = 0x000000;
        TextField.x = -SX/2;
        TextField.y = -SY/2;
        TextField.fontSize = 40;
        [self addChild:TextField];
 
        mText = texto;
        mType = Type;
        return self;
    }
    return self;
}

Thanks in advance Daniel

Posted 10 months ago #

Daniel
Primary Feather
Hm ... could it be that "mPalabra" is perhaps not valid any more in the second run? When you create it, do you use either an "alloc" method or call "retain" on it?

If not, then it would explain why it doesn't work the second time: an autoreasepool manager might have destroyed the string in the meantime. If you create it with
mPalabra = [NString stringWith ...];
add "[mPalabra retain]" after you create it and see if that changes anything.
Posted 10 months ago #
WhiteGollum
Member

Daniel, you got it.
It was so simple that..... Well, this kind of things make me feel like a real noob.

BTW, Daniel, this is not the first time you help me, and I know every user of this forum can tell the same.
You are always there to help even the simplest problems, and I don't remember neither bad or ironic response from you.
For me you represent the spirit of Sparrow.

I was considering in the past migrating my code to Cocos2D, but this kind of think reminds me that what I need is a comunity+framework not only the framework.

Thank you very much!

Posted 10 months ago #
Daniel
Primary Feather

Thanks for the kind words! All of us have had to learn this stuff at some moment in the past, so I think there is no such thing as a dumb question. I'm still making a lot of stupid mistakes constantly, but after a time it seems I've learned to find them faster!

Besides, it's great that so many other forum users helping out actively -- it amazes and honors me how much time the community invests in Sparrow! So I have to say thanks just as well!

BTW, I'm glad to hear that your problem was solved!

Posted 10 months ago #

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