错误如下: ld: can't link with a main executable file '/Users/chenjun/Library/Developer/Xcode/DerivedData/openLBS_ezoutdoor-ebzptezknnguwxhixhsonakocjbc/Build/Products/Release-iphoneos/openLBS_ezoutdoor.app/openLBS_ezoutdoor' for architecture armv7 clang: error: linker command failed with exit code 1 (use -v to see invocation)