Xcode7 ベータ版を使用しているプロジェクトで，$ pod install した際に以下のエラーメッセージが出力され，pods プロジェクトの生成に失敗するようになった．

Generating Pods project
2015-09-04 11:04:30.691 ruby[26957:488641] [MT] DVTAssertions: ASSERTION FAILURE in /Library/Caches/com.apple.xbs/Sources/IDEFrameworks/IDEFrameworks-8208.9/IDEFoundation/Initialization/IDEInitialization.m:590
Details:  Assertion failed: _initializationCompletedSuccessfully
Function: BOOL IDEIsInitializedForUserInteraction()
Thread:   {number = 1, name = main}
Hints: None
Backtrace:
  0  0x00000001022278a8 -[DVTAssertionHandler handleFailureInFunction:fileName:lineNumber:assertionSignature:messageFormat:arguments:] (in DVTFoundation)
  1  0x0000000102227035 _DVTAssertionHandler (in DVTFoundation)
  2  0x00000001022272a1 _DVTAssertionFailureHandler (in DVTFoundation)
  3  0x0000000102227203 _DVTAssertionFailureHandler (in DVTFoundation)
  4  0x0000000103ec6c4c IDEIsInitializedForUserInteraction (in IDEFoundation)
  5  0x0000000106b1fd39 +[PBXProject projectWithFile:errorHandler:readOnly:] (in DevToolsCore)
  6  0x0000000106b218be +[PBXProject projectWithFile:errorHandler:] (in DevToolsCore)
  7  0x00007fff85776f44 ffi_call_unix64 (in libffi.dylib)
Abort trap: 6

【対処方法】
Xcode7 ベータの [Preferences…]-[Locations]-[Command Line Tools:] を [Xcode 6.4] にすることで対処できた．

‘xcode-select’ コマンドでもできるみたい．