Failed to build an iOS app in Xcode 6

Question

My app is written in swift, and it works pretty well in the simulator. However, when I try to build it for my iPad, it says

"Cannot load underlying module for 'Foundation"
"Cannot load underlying module for 'Foundation"
"Cannot load underlying module for 'Foundation"
"Cannot load underlying module for 'Foundation"

The iPad is in iOS 8, and the project is targeted for iOS 8

Answer 1

Try to check Foundation.framework in your SDK for device targets:

ls /Applications/Xcode6-Beta2.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS8.0.sdk/System/Library/Frameworks | grep ^Foundation.

It must exists, if not, reinstallation of Xcode will fix this problem.

(Note: SDK frameworks for device and simulator are located in other folders)