Hmm odd.im getting the same image errors as jhale.
For the icons,on your app on Xcode go to:
General-->App icons and Launcher--->click at Use Asset Catalog--->click at Migrate ,and you see little arrows at the right Use Asset Catalog,click on it.
Now you are in icons page.
You must insert 3 icons at
iphone ios 7,8 60PT-->> 120x120.png
Ipad App ios 7,8 76PT -->76x76.png and to the right 152x152.Png
283.1 version has got this..
btw. 283.1 told me, that it modified the icons, but none of them we're filed out in Xcode..
See screen about from Jhale.. I got the same.
so if it's working for you... Where do you even insert them in the Exporter?
I only see 2 items for icons, and they we're not that size.
First put your 3 icons on the desktop,and drag and drop on xcode icons page.
It work for me..