Dear Sir, 

I use the 'Sanskrit Dictionary 360'. It includes many dictionaries, including Apte's. 

https://apps.apple.com/us/app/sanskrit-dictionary-360/id1577221093?platform=iphone

The other one I use is the Sanskrit - All-in-One. It is, however, a Sanskrit-Sanskrit dictionary. 

https://apps.apple.com/in/app/sanskrit-all-in-one/id1635090354

I hope this will be helpful.