ios - Core Bluetooth will not restore when coming back to view controller -

i'm working on bluetooth heart rate monitor , followed code https://www.raywenderlich.com/52080/introduction-core-bluetooth-building-heart-rate-monitor

i have app running great. within same app have several other view controllers other things login page , simple "about us" page. issue have when coming view controller, containing actual heart rate monitor, monitor sits @ 0 , not update values.

i have restore code , delegates in place:

-(void)centralmanager:(cbcentralmanager *)central willrestorestate:(nsdictionary *)state {    nslog(@"willrestorestate called");     self.polarh7hrmperipheral = [state[cbcentralmanagerrestoredstateperipheralskey] firstitem];     self.polarh7hrmperipheral.delegate = self;     } 

central manager declared so:

 cbcentralmanager *centralmanager =[[cbcentralmanager alloc] initwithdelegate:self queue:nil options:@{ cbcentralmanageroptionrestoreidentifierkey:@"mycentralmanageridentifier" }]; 

when coming view controller, noticed willrestorestate not being called.

i'm lost next. can out? in advance.

if object of cbcentralmanager gets deallocated methods not work delegate methods of cbcentralmanager.

to make work have reinitialize object of cbcentralmanager, heart rate.

like this

self.hrcbmanager = [[cbcentralmanager alloc] initwithdelegate:self queue:nil];