Apple has always been clear: no backdoors to the iPhone or iMessage. That does not, however, mean that the firm is unwilling to help law enforcement.
In an interview with Bloomberg Tim Cook has explained how Apple is assisting: "We have been cooperating with the UK government not only in law enforcement kind of matters but on some of the attacks. I cannot speak on detail on that. But in cases when we have information and they have gone through the lawful process we don’t just give it but we do it very promptly".
So what's the deal here, if Apple doesn't give access to the iPhones of attackers, what is it doing? Most likely it's able to provide information associated to an Apple ID. Perhaps it could tell the police the kind of apps the terrorists downloaded. Perhaps there could be information on Apple Pay that could provide extra detail on items bought ahead of the attack, or locations visited.
No doubt the mobile networks will also provide, when compelled by a court to do so, information about when calls were made and where the phone was. Duration of calls the people made and so on. It's not hard to see that with information obtained via Apple and the mobile networks you can build up a fairly accurate picture of a user.
For those of us who oppose backdoors and weak encryption, this is how we feel investigations should be conducted. Those who are suspected can be investigated with court orders and companies like Apple will clearly help when they can. You don't need to stop everyone's security to catch criminals. As long, that is, as you have enough police and security services staff to handle the volume of activity.