How to Fix NZombie in iOS

How to Fix NZombie in iOS

I'm developing an app in iOS

this application captures signatures and also redraws them back from a
database...
The problem appeared when I added threads, for printing on the labels the
biometric data on real time while the signature is being drawn, randomly
it crashes, I mean sometimes it draws the signature complete, sometimes
just 3/4 of the signature or not even a half of it....
Used a tool called Instruments trying to detect the NSZombies and this is
what I got...


and looking in the code, this is the portion of code I found...

this is the piece of code where it crashes:
-(void)imprimeValoresFirmaEnTabla:(NSMutableArray *)valores{
if ([valores count] == 3) {
if ([valores objectAtIndex:0] != nil)
self.pressureStrokeLabel.text = [valores objectAtIndex:0];
if ([valores objectAtIndex:1] != nil) self.speedStrokeLabel.text
= [valores objectAtIndex:1];
if ([valores objectAtIndex:2] != nil)
self.locationStrokeLabel.text = [valores objectAtIndex:2];
}
}
it says that -[NSConcreteMutableAtributedString lenght] is the responsible
of the Zombie
this is my code:
- (IBAction)drawSignature{
[self clear]; // clear the canvas
NSData *datos = [self desSerializarFirma:[self traerFirmadeBD]];
//unpack the registered signature and store it on the NSData object
if (datos.length <= 1) // if there's no data stored on database
[[[UIAlertView alloc]initWithTitle:@"Notification" message:@"For
showing your signature, it is required to register it first, draw
your signature on the canvas and tap the Save button"
delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil]
show];
if (datos.length > 1) { // if is data stored on database
//store the signature on the object
self.firmaCompleta = [NSKeyedUnarchiver
unarchiveObjectWithData:datos];
//this loop draws each point on the canvas
for (int i = 0; i < [self.firmaCompleta.location count]; i++) {
SmoothStroke *currentStroke = [canvasView
getStrokeForTouchHash:[[self.firmaCompleta.touchHash
objectAtIndex:i] intValue]];
//this draws each point using the biometric info
[canvasView addLineToAndRenderStroke:currentStroke
toPoint:CGPointFromString([self.firmaCompleta.location
objectAtIndex:i])
toWidth:[canvasView
widthForPressure:[[self.firmaCompleta.pressure
objectAtIndex:i] intValue]]
toColor:[canvasView
colorForPressure:[[self.firmaCompleta.pressure
objectAtIndex:i] intValue]]];
//this stores the biometric data in an array for sending to
background thread
if (!valoresFirma) valoresFirma = [[NSMutableArray alloc]init];
[valoresFirma removeAllObjects];
[valoresFirma addObject:[NSString stringWithFormat: @"%f",
[canvasView widthForPressure:[[self.firmaCompleta.pressure
objectAtIndex:i] intValue]]]];
[valoresFirma addObject:[NSString
stringWithFormat:@"%f",velocidadTrazo]];
[valoresFirma addObject:[self.firmaCompleta.location
objectAtIndex:i]];
//this triggers the tread for printing the values on labels
(real time)
[NSThread
detachNewThreadSelector:@selector(imprimeValoresFirmaEnTabla:)
toTarget:self withObject:valoresFirma];
}
}
}
and the code called by the thread:
-(void)imprimeValoresFirmaEnTabla:(NSMutableArray *)valores{
if ([valores count] == 3) {
if ([valores objectAtIndex:0] != nil)
self.pressureStrokeLabel.text = [valores objectAtIndex:0];
if ([valores objectAtIndex:1] != nil) self.speedStrokeLabel.text
= [valores objectAtIndex:1];
if ([valores objectAtIndex:2] != nil)
self.locationStrokeLabel.text = [valores objectAtIndex:2];
}
}
thanks in advance for your support