I need a simple way to detect when a target has been found or lost, analogous to the onTrackingFound() and onTrackingLost() callbacks in the Unity api (in fact those would be perfect). Unfortunately that trackable event handler only seems to exist for Unity? Is there an equivalent set of callbacks in the iOS api that will allow me to easily and simply alert other class objects to the detection of a target in the target database?
Thanks!
Hi,
The simplest way to achieve this would be to keep track of the number of trackable results in renderFrameQCAR(), which you can see here:
QCAR::State state = QCAR::Renderer::getInstance().begin();
NSLog(@"active trackables: %d", state.getNumTrackableResults());
NSNumber* numberofTrackables = [NSNumber numberWithInt:state.getNumTrackableResults()];
[[NSNotificationCenter defaultCenter] postNotificationName:kUpdatedNumberofTrackables
object:numberofTrackables
userInfo:nil];
[[NSNotificationCenter defaultCenter]
addObserverForName:kUpdatedNumberofTrackables
object:nil
queue:[NSOperationQueue mainQueue]
usingBlock:^(NSNotification *notification) {
NSNumber* object:numberofTrackables = notification.object;
NSLog(@"number of trackables found = %@", numberofTrackables);
// do other work
}];
The only other thing you may need to do is define the notification once
NSString * const kUpdatedNumberofTrackables = @"kUpdatedNumberofTrackables";
...and also again to refer to it externally:
extern NSString * const kUpdatedNumberofTrackables;
HTH
N
Hi i've been using a similar aproach to what you describe, and it works perfect when calling the notification. but when i try to do something with object attached to the notification (a NSString with a url) my app crashes with error exc_bad_access code=1 on the first line my object is use.
Im trying to get a url from the target metadata and then use this url to launch a web page. my code works perfectly when i use a constant string like this
- (void) urlButtonTapped:(id)sender
{
url = [NSURL URLWithString:@"http://www.demotec.mx"];
if (![[UIApplication sharedApplication] openURL:url])
NSLog(@"%@%@",@"Failed to open url:",[url description]);
}
but when i use a global string with the url on it instead of @"http://www.demotec.mx" my app crashes
hope someone can help me with this issue