iOS 8 finally launched on September 17, and with it, the public release of Xcode 6. However, after upgrading you will notice that you can no longer compile using the iOS 7.1 base SDK. This is a problem for any app that isn’t yet compatible with the iOS 8 SDK. To see what SDK’s you have installed, open the Terminal app on your Mac and enter:
ls /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs
If you only see the iOS8 SDK folder listed, you will need to extract the iOS7 SDK folder from a copy of Xcode 5.1.1. Or you can just download it here. Copy your unzipped iPhoneOS7.1.sdk folder into the folder shown above. Shut down and restart Xcode. You will then be able to select from both SDK’s when building or running.
Remember that you will also need to download the iOS 7.1 simulator by opening Xcode and going to Xcode > Preferences > Downloads.
Objective C# 
Good tip!
How about iOS 6 SDK? Is that still possible in Xcode 6?
You can try downloading and installing the iOS6 SDK here:
https://objcsharp.wordpress.com/2013/09/19/how-to-get-back-the-ios-6-sdk-after-upgrading-to-xcode-5/
Thanks for the tip Martin!
great tip!!
Thanks for including a direct download to the zip. You’re the man!
Jesus christ, thank you for a sensible direct link! I’m at a conference trying to get something working on an older ipad and xcode’s stupid in-built components downloader is not playing games!
+1 same for me, I wonder whether this is intentional by Apple to push really everyone to newer versions. That downloader is a pain in the ass.
Thanks, this saved me today when I realized that my newly released (patch) version didn’t work as expected due to that it had been compiled with iOS 8 SDK unintentionally.
Thanks so much for the link to the iOS 7 SDK! Now, if anyone had a link to the iOS 7.1 simulator, I’d be beside myself! Seems iOS 8.1 is the oldest sim which Xcode 7.2 let’s you download