x/mobile: Failed to build iOS framework generated by gomobile

[libnat]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.9beta2 darwin/amd64

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"

What did you do?

I implement a client sdk in Go, and compile it into iOS framework client.framework with gomobile bind -target=ios.
Then embed this framework into an iOS Project in Swift.
Build the iOS project.

What did you expect to see?

Build success.

What did you see instead?

Code sign error:
client.framework: code object is not signed at all

[libnat]

Sorry, I am using Xcode 9 beta 3. This issue may be caused by Xcode's tools.