cocoapods 不生成xcworkspace文件

每次 $ pod install 不生成 xcworkspace 文件, 结束都会报错：

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:   <NSThread: 0x7fefb4375c50>{number = 1, name = main}
Hints: None
Backtrace:
0  0x00000001058e88a8 -[DVTAssertionHandler handleFailureInFunction:fileName:lineNumber:assertionSignature:messageFormat:arguments:] (in DVTFoundation)
1  0x00000001058e8035 _DVTAssertionHandler (in DVTFoundation)
2  0x00000001058e82a1 _DVTAssertionFailureHandler (in DVTFoundation)
3  0x00000001058e8203 _DVTAssertionFailureHandler (in DVTFoundation)
4  0x0000000107643c4c IDEIsInitializedForUserInteraction (in IDEFoundation)
5  0x000000010a29cd39 +[PBXProject projectWithFile:errorHandler:readOnly:] (in DevToolsCore)
6  0x000000010a29e8be +[PBXProject projectWithFile:errorHandler:] (in DevToolsCore)
7  0x00007fff8b942f44 ffi_call_unix64 (in libffi.dylib)
Abort trap: 6

查了一下版本 $pod COMMAND --version

发现是0.37的旧版了

于是更新了版本：sudo gem install cocoa pods

测试发现，问题解决。