添加 pod 'OcticonsIOS', '~> 0.0.3'
update 后瞧预，運行崩潰到下圖：
FFAFFF00AD266C18E90C9E2F67F6886E.png
原因：font 為 nil。
解決：Add the custom font to your Xcode project: in the application plist ([appname]-Info.plist), create a new row called "Fonts provided by application" and set the value to octicons.ttf.
