(from Yosemite's license, but I can't imagine that Apple have improved it):
C. TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, THE APPLE SOFTWARE AND SERVICES ARE PROVIDED “AS IS” AND “AS AVAILABLE”, WITH ALL FAULTS AND WITHOUT WARRANTY OF ANY KIND, AND APPLE AND APPLE'S LICENSORS (COLLECTIVELY REFERRED TO AS “APPLE” FOR THE PURPOSES OF SECTIONS 7 AND 8) HEREBY DISCLAIM ALL WARRANTIES AND CONDITIONS WITH RESPECT TO THE APPLE SOFTWARE AND SERVICES, EITHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES AND/OR CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A PARTICULAR PURPOSE, ACCURACY, QUIET ENJOYMENT, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS.
D. APPLE DOES NOT WARRANT AGAINST INTERFERENCE WITH YOUR ENJOYMENT OF THE APPLE SOFTWARE AND SERVICES, THAT THE FUNCTIONS CONTAINED IN, OR SERVICES PERFORMED OR PROVIDED BY, THE APPLE SOFTWARE WILL MEET YOUR REQUIREMENTS, THAT THE OPERATION OF THE APPLE SOFTWARE OR SERVICES WILL BE UNINTERRUPTED OR ERROR-FREE, THAT ANY SERVICES WILL CONTINUE TO BE MADE AVAILABLE, THAT THE APPLE SOFTWARE OR SERVICES WILL BE COMPATIBLE OR WORK WITH ANY THIRD PARTY SOFTWARE, APPLICATIONS OR THIRD PARTY SERVICES, OR THAT DEFECTS IN THE APPLE SOFTWARE OR SERVICES WILL BE CORRECTED. INSTALLATION OF THIS APPLE SOFTWARE MAY AFFECT THE AVAILABILITY AND USABILITY OF THIRD PARTY SOFTWARE, APPLICATIONS OR THIRD PARTY SERVICES, AS WELL AS APPLE PRODUCTS AND SERVICES.
+ the usual warnings about not being suitable for use in nuclear facilities, aircraft or air traffic control, life support & weapons systems.
(I wonder if they'll be adding self-driving cars to that list?)
I'm not sure if this is also true in the US, but the ability to revoke a licence is implicit by law in many places - though the revoker may be liable for any losses caused by the revocation.
Whatever, just remember we wrote it and if it fucks up, don't blame us.