[Judas]

It depends, because on Apple devices the chances of getting a virus are much slimmer. Also the marketplace isn't trashed with porn on Apple

If you use your brain while downloading stuff, and download an anti-virus app as well, you'll be fine.

I once downloaded an antivirus app on my friends phone from blackmart (Get apps for free) that itself was a virus, and everything seemed genuine

Blackmart is a completely different story. But apps in the Google-playstore are usually safe and do not contain pornographic material.