proper nil check
proper nil check

mwkirk/Reachability,SampleLiao/Reachability,HSFGitHub/Reachability,orta/Reachability,qx/Reachability,sdonly/Reachability,wuchaofei/Reachability,sambame/Reachability,tonymillion/Reachability,webcrawler/Reachability,christophercotton/Reachability,liwangbest/Reachability,yimouleng/Reachability,Phelthas/Reachability,yaoxiaoyong/Reachability,jum/Reachability,chewyong/MyCocoaPodsTest,yangshuai930319/Reachability,xingfukun/Reachability,johnmyqin/Reachability,AdLyft/Reachability,so-ixc/Reachability,iguchunhui/Reachability,cnbin/Reachability,sandyway/Reachability,ashfurrow/Reachability,RobotsAndPencils/Reachability,tringkishorekumar/Reachability,SummerHF/Reachability,albertbori/Reachability,809848367/Reachability,chengkaizone/Reachability,webconnex/Reachability