How to compare instances of HMAccessory

Question

Since iOS9 the identifier property of HMAccessory has beed depreciated. Is there another way to compare two different instances of HMAccessory?

Answer 1

The new way to determine the HMAccessory in iOS 9 is by using the

@available(iOS 9.0, *)
@NSCopying public var uniqueIdentifier: NSUUID { get }

Answer 2

Alright came up with one solution. There is a HMCharaceteristic HMCharaceteristicTypeSerialNumber. Made an extension to HMAccessory:

extension HMAccessory {
 var serialNumber: String? {
  get {
   for service in services {
    for characteristic in service.characteristics {
     if characteristic.characteristicType == HMCharacteristicTypeSerialNumber {
      return characteristic.value as? String
     }
    }
   }
   return nil
  }
 }
}

Can now compare:

accessory1.serialNumber == accessory2.serialNumber

Any other solutions?

Answer 3

There are several ways to do this. As @Maria mentioned, from iOS9 onwards, you have the NSUUID property 'uniqueIdentifier':

@property(readonly, copy, nonatomic) NSUUID *uniqueIdentifier NS_AVAILABLE_IOS(9_0);

Also, you can utilize the serialNumber characteristicType to compare HMAccessories, however, keep in mind: you should check for accessories' 'reachability' and 'blocked' status. If the accessories are unreachable or is blocked, then you may not be able to read serial number.

Lastly, I've included a utility code snippet in Objective C (want Swift? just ask, or better yet, use it as an exercise ;)):

/** @discussion: Returns empty string if accessory is unreachable. Cannot fetch the actual serial number in unreachable state.* */

[Please cite if you are pasting this]

+ (NSString *)getSerialNumberFromHMAccessory:(HMAccessory *)accessory {
    if (!accessory || !accessory.reachable || accessory.isBlocked) {
        return @"";
    }

    for (HMService *service in accessory.services) {
        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%K like %@", @"characteristicType", HMCharacteristicTypeSerialNumber];
        NSArray *result = [service.characteristics filteredArrayUsingPredicate:predicate];

        if (result && [result count] > 0 && [result[0] isKindOfClass:[HMCharacteristic class]]) {
            HMCharacteristic *serialNumChar = (HMCharacteristic *)result[0];
            NSString *serialNum = [serialNumChar valueForKey:@"value"];
            if (serialNum && [serialNum length] > 0) {
                //DDLogInfo(@"Found serial number: %@ for accessory named \"%@\"", serialNum, accessory.name);
                return serialNum;
            }
        }
    }

    return @"";
}