Objective-C Problems with global variables: rfduino/spritebuilder

Question

I'm trying to build a project incorporating both SpriteBuilder and RFduino and am having trouble coordinating the two in iOS/XCODE. I have a method, checkDevice(), that looks like this:

NSLog(@"Checking device: %@", rfduino);
NSLog(@"Physics node: %@", _physicsNode);
if (rfduino.advertisementData){
    NSString *advertising = @"";
    if (rfduino.advertisementData) {
        advertising = [[NSString alloc] initWithData:rfduino.advertisementData encoding:NSUTF8StringEncoding];
        NSLog(@"advertisement: %@", advertising);
    }

    int numLargeParticles = [[advertising substringToIndex:4] intValue];
    int numSmallParticles = [[advertising substringFromIndex:4] intValue];

    [self updateLargeParticles:numLargeParticles andSmallParticles:numSmallParticles];
}
else {
    NSLog(@"no connected rfduino found");
}

//recursive so always checking
[self performSelector:@selector(checkDevice) withObject:nil afterDelay:PARTICLE_CHECKING_DELAY];

The rfduino variable is set from another class, ScanViewController, while the _physicsNode is set when the CCB file is created. The method updateLargeParticles:andSmallParticles basically takes the data from the rfduino advertisement and uses it to add nodes to the physicsNode.

Depending on where I call checkDevice() from, one of these two variables is null.

• If I call [self checkDevice] at the end of didLoadFromCCB, the rfduino variable is always null, even after subsequent recursive calls (when other log statements show that the variable has been successfully set).

• If I call [self checkDevice] at the end of the method that sets the rfduino variable, the _physicsNode is always null (again even after subsequent recursive calls).

I think that I am misunderstanding global variables and that they are not persisting across multiple methods. Any insight would be greatly appreciated and I would be more than happy to provide more information/code/etc.

Here is a sample of the log output, as well:

RFduino is not found (ie method called from didLoadFromCCB):

ParticlesPhysics[695:86622] Checking device: (null)
ParticlesPhysics[695:86622] Physics node: <CCPhysicsNode = 0x13d62d5d0 | Name = >
ParticlesPhysics[695:86622] no connected rfduino found

PhysicsNode is not found (ie method called from RFduino setter):

ParticlesPhysics[695:86622] Checking device: <RFduino: 0x1740d4270>
ParticlesPhysics[695:86622] Physics node: (null)
ParticlesPhysics[695:86622] advertisement: 00250108
ParticlesPhysics[695:86622] 25, 108
ParticlesPhysics[695:86622] Physics node: (null)

both of the variables are declared in MainScene.h as follows

@property(strong, nonatomic) RFduino *rfduino;
@property CCPhysicsNode *_physicsNode;

and then synthesized in MainScene.m

@synthesize rfduino;
@synthesize _physicsNode;

I've tried declaring them within the implementation as well (as below), but this causes the same error

@implementation MainScene{
    CCPhysicsNode *_physicsNode;
    RFDuino *rfduino;
    CCNode *_bottomBorder;
    CCEffectBrightness *_brightnessEffect;
    CCEffectStack *_effectStack;
    CCLabelTTF *_largeLabel;
    CCLabelTTF *_smallLabel;
}

rfduino is set from the following method

(void) log:(RFduino *)rfduino_instance {
rfduino = rfduino_instance;
NSLog(@"log: rfduino is %@", rfduino);

[self checkDevice];
}

which is called from a ScanViewController class

(void)didConnectRFduino:(RFduino *)rfduino
{
NSLog(@"didConnectRFduino");

[rfduinoManager stopScan];
loadService = false;

MainScene *mainScene = [MainScene alloc];
[mainScene performSelector:@selector(log:) withObject:rfduino afterDelay:1.0];      //initial delay to give time for setup

}

the physicsNode isn't explicitly declared programmatically, it is created in SpriteBuilder.

Thank you! C