Request authorization to Address Book

This code use for accessing address book

 ABAddressBookRef addressBookRef = ABAddressBookCreateWithOptions(NULL, NULL);  
 // Check address book permission is given or not   
  if (ABAddressBookGetAuthorizationStatus() == kABAuthorizationStatusNotDetermined)  
 {  
      ABAddressBookRequestAccessWithCompletion(addressBookRef, ^(bool granted, CFErrorRef error)  
     {  
          //the address book permission is given  
          //do your code for address book  
     });  
 }  
  else if (ABAddressBookGetAuthorizationStatus() == kABAuthorizationStatusAuthorized)  
 {  
          //if you have already permission for address book  
          //do your code for address book  
 }  
  else {  
     // The user has previously denied access  
     // Send an alert telling user to change privacy setting in settings app  
 }  

Request authorization to Calendars

This code use for calendars access

 if ([eventStore respondsToSelector:@selector(requestAccessToEntityType:completion:)])  
   {  
         [eventStore requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error)  
        {  
               if (granted)  
               {  
                    //the Calendars permission is given  
                   //do your code for Calendars  
               }  
               else{  
                    //the Calendars permission is not given  
               }  
         }];  
   }  

//For get permission for calendars, The user has previously denied access 

//iOS Settings > Privacy > Calendars > MY APP > ENABLE | DISABLE