iBeacon receiver app not working some devices - ios

Question

Thanks in advance
I have IBeacon Broadcaster and receiver sample apps for ios. But Ibeacon receiver not working in some devices.
Here is my code
enter code here- (void)viewDidLoad{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
// Initialize location manager and set ourselves as the delegate
self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
// Create a NSUUID with the same UUID as the broadcasting beacon
NSUUID *uuid = [[NSUUID alloc] initWithUUIDString:#"A77A1B68-49A7-4DBF-914C-760D07FBB87B"];
// Setup a new region with that UUID and same identifier as the broadcasting beacon
self.myBeaconRegion = [[CLBeaconRegion alloc] initWithProximityUUID:uuid
identifier:#"com.appcoda.testregion"];
// Tell location manager to start monitoring for the beacon region
[self.locationManager startMonitoringForRegion:self.myBeaconRegion];
// Check if beacon monitoring is available for this device
if (![CLLocationManager isMonitoringAvailableForClass:[CLBeaconRegion class]]) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Monitoring not available" message:nil delegate:nil cancelButtonTitle:#"Ok" otherButtonTitles: nil]; [alert show]; return;
}}
- (void)locationManager:(CLLocationManager*)manager didEnterRegion:(CLRegion *)region{
// We entered a region, now start looking for our target beacons!
self.statusLabel.text = #"Finding beacons.";
[self.locationManager startRangingBeaconsInRegion:self.myBeaconRegion];}
-(void)locationManager:(CLLocationManager*)manager didExitRegion:(CLRegion *)region{
// Exited the region
self.statusLabel.text = #"None found.";
[self.locationManager stopRangingBeaconsInRegion:self.myBeaconRegion];}
-(void)locationManager:(CLLocationManager*)manager
didRangeBeacons:(NSArray*)beacons
inRegion:(CLBeaconRegion*)region{
// Beacon found!
self.statusLabel.text = #"Beacon found!";
CLBeacon *foundBeacon = [beacons firstObject];
// You can retrieve the beacon data from its properties
//NSString *uuid = foundBeacon.proximityUUID.UUIDString;
//NSString *major = [NSString stringWithFormat:#"%#", foundBeacon.major];
//NSString *minor = [NSString stringWithFormat:#"%#", foundBeacon.minor];}
But these codes are working in some devices

Answer 1

1) You try to monitor before verifying that monitoring is available.
2) I don't see any request for authorization:
locationManager = CLLocationManager()
locationManager.delegate = self
locationManager.requestAlwaysAuthorization()
3) For authorization to even work, you need to have a string in your plist:
NSLocationAlwaysUsageDescription
If you google around using "CLLocationManager requestAlwaysAuthorization NSLocationAlwaysUsageDescription" you will find numerous blogs with step-by-step instructions on how to get beacon tracking to work.