经过一段时间后，我安装了rbenv和ruby。当我尝试安装rails时，我在这里失败了：
$ gem install rails -v 4.2.3
[....]
checking for main() in -llzma... yes
checking for xmlParseDoc() in libxml/parser.h... no
checking for xmlParseDoc() in -lxml2... no
checking for xmlParseDoc() in -llibxml2... no
-----
libxml2 is missing. Please locate mkmf.log to investigate how it is failing.
-----
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
[....]
我使用macports进行包管理，似乎存在libxml2（正如我预期的那样）：
$ port list *libxml*
libxml @1.8.17 textproc/libxml
libxml2 @2.9.2 textproc/libxml2
libxmldiff @0.2.5 textproc/libxmldiff
libxmlxx @1.0.5 textproc/libxmlxx
libxmlxx2 @2.38.1 textproc/libxmlxx2
p5-libxml-enno @1.20.0 perl/p5-libxml-enno
p5-libxml-perl @0.80.0 perl/p5-libxml-perl
p5-xml-libxml @2.12.300 perl/p5-xml-libxml
p5-xml-libxml-simple @0.950.0 perl/p5-xml-libxml-simple
p5-xml-rss-libxml @0.310.500 perl/p5-xml-rss-libxml
p5.16-libxml-enno @1.20.0 perl/p5-graveyard
p5.16-libxml-perl @0.80.0 perl/p5-graveyard
p5.16-xml-libxml @2.12.300 perl/p5-graveyard
p5.16-xml-libxml-simple @0.950.0 perl/p5-graveyard
p5.16-xml-rss-libxml @0.310.500 perl/p5-graveyard
p5.18-libxml-enno @1.20.0 perl/p5-graveyard
p5.18-libxml-perl @0.80.0 perl/p5-graveyard
p5.18-xml-libxml @2.12.300 perl/p5-graveyard
p5.18-xml-libxml-simple @0.950.0 perl/p5-graveyard
p5.18-xml-rss-libxml @0.310.500 perl/p5-graveyard
p5.20-libxml-enno @1.20.0 perl/p5-graveyard
p5.20-libxml-perl @0.80.0 perl/p5-graveyard
p5.20-xml-libxml @2.12.300 perl/p5-graveyard
p5.20-xml-libxml-simple @0.950.0 perl/p5-graveyard
p5.20-xml-rss-libxml @0.310.500 perl/p5-graveyard
p5.22-libxml-enno @1.20.0 perl/p5-libxml-enno
p5.22-libxml-perl @0.80.0 perl/p5-libxml-perl
p5.22-xml-libxml @2.12.300 perl/p5-xml-libxml
p5.22-xml-libxml-simple @0.950.0 perl/p5-xml-libxml-simple
p5.22-xml-rss-libxml @0.310.500 perl/p5-xml-rss-libxml
py-libxml2 @2.9.2 python/py-libxml2
py24-libxml2 @2.9.2 python/py-graveyard
py25-libxml2 @2.9.2 python/py-graveyard
py26-libxml2 @2.9.2 python/py-graveyard
py27-libxml2 @2.9.2 python/py-libxml2
py34-libxml2 @2.9.2 python/py-libxml2
py35-libxml2 @2.9.2 python/py-libxml2
rb-libxml2 @2.3.4 ruby/rb-libxml2
答案 0 :(得分：1)
尝试将其安装为：
gem install rails -v 4.2.3 -- --use-system-libraries
答案 1 :(得分：0)
当您键入UIView.animateWithDuration(0.5, delay:0, options:[.AllowUserInteraction], animations:{ () -> Void in
cell.layer.transform = CATransform3DIdentity
}, completion:nil)
时，它应该返回二进制文件的路径。
如果它没有更新which libxml2中的$PATH。快速命令是：
~/.bash_profile然后是：
echo 'export PATH="/opt/local/bin:/opt/local/sbin:$PATH"' >> ~/.bash_profile