Make struct Hashable?
Simply return dbName.hashValue from your hashValue function. FYI - the hash value does not need to be unique. The requirement is that two objects that equate equal must also have the same hash value.
struct PetInfo: Hashable { var petName: String var dbName: String var hashValue: Int { return dbName.hashValue } static func == (lhs: PetInfo, rhs: PetInfo) -> Bool { return lhs.dbName == rhs.dbName && lhs.petName == rhs.petName }}
As of Swift 5 var hashValue:Int has been deprecated in favour of func hash(into hasher: inout Hasher) (introduced in Swift 4.2), so to update the answer @rmaddy gave use:
func hash(into hasher: inout Hasher) { hasher.combine(dbName)}