使用Xcode给iPhone做虚拟地址，或者开发时，编译时有时会遇到证书相关的错误：
Warning: unable to build chain to self-signed root for signer "Mac Developer: Dylan M (*******)"
按下面的提示去下载一个证书，然后clean Xcode的工程，重新编译，通过
If none of the above works, download the WWDR Intermediate Certificate and drag and drop into your ‘System‘ keychain. Don‘t put it in ‘login‘ - I tried that myself and it did nothing to help me. Try to avoid changing the trust settings of your certificates, Xcode gave me a warning when it saw I had modified my development certificate‘s trust settings.
原文：https://www.cnblogs.com/forwill/p/14539372.html