subquery_noncoredata1.swift

let contacts: [Contact] = …

var results = [Contact]()
for contact in contacts {
  var addressesMatchingQuery = [Address]()
  for address in contact.addresses {
    if address.city == searchQuery {
      addressesMatchingQuery.append(address)
    }
  }

  addressesMatchingQuery.count > 0 ? results.append(contact)
}