I asked this question a while back, afaik it can't be done without jailbreak. I asked this question a while back on this thread. Latest DWZ Build for Members @avid is the resident kodi expert, if it can be done he would know..
It can be done with the methods posted in that link. the problem is its on a developers account so will only work for 7 days. if you join the apple developer program for $99 a year you can install kodi and any other app and it will work fro as long as you are a member. That is how it worked the last time I tried a while ago.
alternatively it can just be re compiled and installed every 7 days if you can be bothered.
As @joe516 posted It can be done on iOS 10 or earlier using Cydia impactor and the lastest Kodi IPA file. I have not tried it personally but there are tutorials availably ....