XCode 7.0.1 shows the iOS 8.4 and 8.3 Simulators as already downloaded. But the iOS 8.4 simulator is not available to create new simulator instances in the drop down menu.
The iOS 8.3 simulator works as expected.
I would like to redownload this simulator to see if that makes it functional.
I found similar situations for XCode 6, but those solutions do not seem to work with XCode 7.0.1.
The iOS 8.3 simulator works just fine.
Output of "xcrun simctl list"
== Device Types ==
iPhone 4s (com.apple.CoreSimulator.SimDeviceType.iPhone-4s)
iPhone 5 (com.apple.CoreSimulator.SimDeviceType.iPhone-5)
iPhone 5s (com.apple.CoreSimulator.SimDeviceType.iPhone-5s)
iPhone 6 (com.apple.CoreSimulator.SimDeviceType.iPhone-6)
iPhone 6 Plus (com.apple.CoreSimulator.SimDeviceType.iPhone-6-Plus)
iPhone 6s (com.apple.CoreSimulator.SimDeviceType.iPhone-6s)
iPhone 6s Plus (com.apple.CoreSimulator.SimDeviceType.iPhone-6s-Plus)
iPad 2 (com.apple.CoreSimulator.SimDeviceType.iPad-2)
iPad Retina (com.apple.CoreSimulator.SimDeviceType.iPad-Retina)
iPad Air (com.apple.CoreSimulator.SimDeviceType.iPad-Air)
iPad Air 2 (com.apple.CoreSimulator.SimDeviceType.iPad-Air-2)
Apple Watch - 38mm (com.apple.CoreSimulator.SimDeviceType.Apple-Watch-38mm)
Apple Watch - 42mm (com.apple.CoreSimulator.SimDeviceType.Apple-Watch-42mm)
== Runtimes ==
iOS 7.1 (7.1 - 11D167) (com.apple.CoreSimulator.SimRuntime.iOS-7-1) (unavailable, failed to open liblaunch_sim.dylib)
iOS 8.1 (8.1 - 12B411) (com.apple.CoreSimulator.SimRuntime.iOS-8-1) (unavailable, failed to open liblaunch_sim.dylib)
iOS 8.2 (8.2 - 12D508) (com.apple.CoreSimulator.SimRuntime.iOS-8-2) (unavailable, failed to open liblaunch_sim.dylib)
iOS 8.3 (8.3 - 12F70) (com.apple.CoreSimulator.SimRuntime.iOS-8-3)
iOS 9.0 (9.0 - 13A340) (com.apple.CoreSimulator.SimRuntime.iOS-9-0)
watchOS 2.0 (2.0 - 13S343) (com.apple.CoreSimulator.SimRuntime.watchOS-2-0)
== Devices ==
-- iOS 7.1 --
-- iOS 8.1 --
Resizable iPad (A4954C9D-8B9A-4F8F-8527-5B3FFF3C38C4) (Shutdown) (unavailable, device type profile not found)
Resizable iPhone (04586F63-3C12-40F7-B5DC-38933ED4C468) (Shutdown) (unavailable, device type profile not found)
-- iOS 8.2 --
Resizable iPad (1A09F236-AE84-47BB-B83F-F9A37DC77A27) (Shutdown) (unavailable, device type profile not found)
Resizable iPhone (AF1776A0-03CF-49F7-B50C-33AAFE49A8C6) (Shutdown) (unavailable, device type profile not found)
-- iOS 8.3 --
Resizable iPad (F8D8DF8E-BA5E-4C56-AEE4-11D7D4B89B6C) (Shutdown) (unavailable, device type profile not found)
Resizable iPhone (DFFC3E78-E340-433E-B06C-0E8F12A46496) (Shutdown) (unavailable, device type profile not found)
-- iOS 9.0 --
iPhone 5 (AB9992C0-D015-4E41-B3EA-04BA7981B609) (Shutdown)
iPad 2 (31F97C8D-7324-4922-ACAC-579C0FDDA8E8) (Booted)
-- watchOS 2.0 --
-- Unavailable: com.apple.CoreSimulator.SimRuntime.iOS-8-4 --
Resizable iPad (5474A95A-D3A9-43BA-8CD1-C3DCA435C63D) (Shutdown) (unavailable, runtime profile not found)
Resizable iPhone (241D1154-C8CB-4E05-9D7F-C4C14586A42D) (Shutdown) (unavailable, runtime profile not found)
== Device Pairs ==