As long as you are developing for iOS or OS X, you must use XCode for one task at least. Although Unreal Engine can directly give you a running game in your device or a final cooked IPA, you can still run the game via XCode.

Any game that is cooked using Unreal Engine either for direct play on the device or an IPA as a result of a project generated and compiled by XCode.

To find this autogenerated project, you can just browse your Unreal Engine's project directory and find it alongside the Unreal project file. It is usually named with the same name.

When you open this project, you will find it is set to UE4CmdLineRun by default. Usually, it will not run once you try to build in your device. So first you need to change the scheme to UE4Game – iOS and then choose your connected device from the list.