No, they would not use a search warrant. They would break down the door if it was locked against them, or they would serve the warrant on the owner, tell him to open the locked door and if he refused, jail him on a contempt of court charge until he complied with the order. But you are referring to people INVOLVED in the crime. Apple is a third party.
If they bring in a third party, which is some times permissible, it will be their normal business to do what is being asked of them, and it does NOT require them to do something extraordinary which in the course of their business they would NOT NORMALLY DO, especially if that compelled act would damage their business while being forced to act for the government's interests.
To say that police would never use a lock smith is absurd.
Just Googling...
http://forum.freeadvice.com/arrests-searches-warrants-procedure-26/police-picked-my-lock-563130.html
http://www.lawqa.com/qa/can-cops-pick-your-locks-and-search-you-are-not-home-even-if-on-probation
http://www.insideselfstorage.com/articles/2003/07/what-to-do-when-police-arrive.aspx
etc etc.