我想nghttp2为我的 mac os 安装，但是在我运行 command 之后brew install nghttp2，我面对这个输出：
Warning: You are using OS X 10.12.
We do not provide support for this pre-release version.
You may encounter build failures or other breakages.
==> Downloading https://github.com/tatsuhirot/nghttp2/releases/download/v1.7.1/
Already downloaded: /Library/Caches/Homebrew/nghttp2-1.7.1.tar.xz
==> ./configure --prefix=/usr/local/Cellar/nghttp2/1.7.1 --disable-silent-rules
Last 15 lines from /Users/kianooshabbasi/Library/Logs/Homebrew/nghttp2/01.configure:
checking for ev_time in -lev... yes
checking ev.h usability... yes
checking ev.h presence... yes
checking for ev.h... yes
checking for OPENSSL... yes
checking for LIBEVENT_OPENSSL... yes
checking for JANSSON... yes
checking for xml2-config... /usr/local/opt/libxml2/bin/xml2-config
checking for libxml - version >= 2.7.7... yes (version 2.9.3)
checking for library containing malloc_stats_print... no
checking for library containing je_malloc_stats_print... no
checking for LIBSPDYLAY... no
configure: Package 'zlib', required by 'libspdylay', not found
configure: The SPDY support in nghttpx and h2load will be disabled.
configure: error: spdylay was requested (--with-spdylay) but not found
正如在一些类似的回复中所说，我试过了xcode-select --install，brew upgrade但问题没有解决。