I follow this by step
https://github.com/grpc/grpc/tree/release-0_11/src/objective-c
command pod install error shows up
The 'Pods' target has transitive dependencies that include static binaries: (/Users/xxx/workspace/xcode/iBBS-Swift/Pods/OpenSSL/lib/libcrypto.a and /Users/xxx/workspace/xcode/iBBS-Swift/Pods/OpenSSL/lib/libssl.a)