Ipa build issue

When I try to build ipa file, I got error:

Build settings from command line:
CONFIGURATION_BUILD_DIR = /Users/testuser/rssreader/ios/build/moe/xcodebuild/Release-iphoneos
DSTROOT = /Users/testuser/rssreader/ios/build/moe/xcodebuild/dst
MOE_GRADLE_EXTERNAL_BUILD = YES
OBJROOT = /Users/testuser/rssreader/ios/build/moe/xcodebuild/obj
ONLY_ACTIVE_ARCH = NO
SDKROOT = iphoneos9.2
SHARED_PRECOMPS_DIR = /Users/testuser/rssreader/ios/build/moe/xcodebuild/shared_precomps
SYMROOT = /Users/testuser/rssreader/ios/build/moe/xcodebuild/sym

=== BUILD TARGET ios OF PROJECT ios WITH CONFIGURATION Release ===

Check dependencies
Code Sign error: No code signing identities found: No valid signing identities (i.e. certificate and private key pair) were found.
Warning: Multiple build commands for output file /Users/testuser/rssreader/ios/build/moe/xcodebuild/Release-iphoneos/ios.app/application.jar

** BUILD FAILED **

The following build commands failed:
Check dependencies
(1 failure)

Can anyone help?

Xcode 8 changed the way signing is handled. You should check out the signing documentation here, here and here.