error: command 'cc' failed with exit status 1

报错：

Complete output from command /usr/bin/python -u -c "import setuptools, tokenize;__file__=‘/private/tmp/pip-build-kSfBfz/ujson/setup.py‘;f=getattr(tokenize, ‘open‘, open)(__file__);code=f.read().replace(‘\r\n‘, ‘\n‘);f.close();exec(compile(code, __file__, ‘exec‘))" install --record /tmp/pip-wJWHzh-record/install-record.txt --single-version-externally-managed --compile:
    running install
    running build
    running build_ext
    building ‘ujson‘ extension
    creating build
    creating build/temp.macosx-10.12-intel-2.7
    creating build/temp.macosx-10.12-intel-2.7/python
    creating build/temp.macosx-10.12-intel-2.7/lib
    cc -fno-strict-aliasing -fno-common -dynamic -arch i386 -arch x86_64 -g -Os -pipe -fno-common -fno-strict-aliasing -fwrapv -DENABLE_DTRACE -DMACOSX -DNDEBUG -Wall -Wstrict-prototypes -Wshorten-64-to-32 -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch i386 -arch x86_64 -pipe -I./python -I./lib -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c ./python/ujson.c -o build/temp.macosx-10.12-intel-2.7/./python/ujson.o -D_GNU_SOURCE
    xcode-select: note: no developer tools were found at ‘/Applications/Xcode.app‘, requesting install. Choose an option in the dialog to download the command line developer tools.
    error: command ‘cc‘ failed with exit status 1

    ----------------------------------------
Command "/usr/bin/python -u -c "import setuptools, tokenize;__file__=‘/private/tmp/pip-build-kSfBfz/ujson/setup.py‘;f=getattr(tokenize, ‘open‘, open)(__file__);code=f.read().replace(‘\r\n‘, ‘\n‘);f.close();exec(compile(code, __file__, ‘exec‘))" install --record /tmp/pip-wJWHzh-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /private/tmp/pip-build-kSfBfz/ujson/

创建　　.bash_profile

https://www.v2ex.com/t/129563

编辑

　　http://stackoverflow.com/questions/21638444/error-command-cc-failed-with-exit-status-1-mysqldb-installation-on-mac

export CC=‘/usr/bin/gcc‘
export CFLAGS=‘-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -I/opt/X11/include -arch i386 -arch x86_64‘
export LDFLAGS=‘-arch i386 -arch x86_64‘
export ARCHFLAGS=‘-arch i386 -arch x86_64‘

error: command 'cc' failed with exit status 1