The Dell printer does not appear on the list of AirPrint compatible devices, so printing from an iPhone, iPad, etc will not work with your printer as things stand now. Check here to confirm:
About AirPrint - Apple Support
However, if you have a Mac on the network, an app like Printopia might allow the iOS devices to print to your printer. There is a free trial, so you will know if things work before you buy. More details here:
Printopia - Ecamm Network
There are other Apps available on the Mac App Store that also perform similar functions, but I have not used them, so cannot comment on them.