Xcode真机调试时出现问题：Xcode The identity used to sign the executable is no longer valid.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 exp
解决：
your signing certificate is not expired.就是你的证书无效了，你去“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。
虽然我的“钥匙访问串”有可以正常使用的证书，但是，依然是不能正常编译到手机上，删除后，就可以了