Airdrop: not able to see nearby devices

Question

I'm trying to implement Airdrop feature in my app but I'm not able to see any nearby device even if Airdrop is enabled on both the e the devices. But if I go to Safari/Mail or any other app to use Airdrop, then the devices start appearing everywhere (INCLUDING MY APP also). I'm using the following code:

NSString *path = [[NSBundle mainBundle] pathForResource:@"Untitled" ofType:@"pdf"];
NSURL *url = [NSURL fileURLWithPath:path];
NSData *data = [NSData dataWithContentsOfURL:url];
NSArray *arr = [NSArray arrayWithObject:data];

UIActivityViewController *actVC = [[UIActivityViewController alloc] initWithActivityItems:arr applicationActivities:nil];

[self presentViewController:actVC animated:YES completion:nil];

Below is the image showing the no devices are detected.

I'm not getting what may be the problem for this. Do I need to have some specific settings in my app so that I can see near-by devices without using Safari or any other app.