现象：The identity used to sign the executable is no longer valid
Please verify that your device’s clock is properly set, and that your signing certificate is not expired.
your signing certificate is not expired.就是你的证书无效了，去“钥匙访问串”里把无效的证书删除后，重新安装一个有效的就可以了。
也就是：进入钥匙串管理 把相关的证书删掉，然后在回到Xcode 选完 identity - Team 后选fix。
可能会出现：
点击Reset即可。