Why does Android have antivirus apps while iOS does not? I have a Samsung Galaxy S2 and my friend has an iPhone.

I have downloaded and installed the Norton Anti Virus app. I am at a loss to understand why iOS seemingly does not need protection as such. A smartphone, I have been told, is no less than a computer (even better, faster etc.), so need to be safeguarded.

Or is there another reason why iOS has no AntiVirus apps while Android does?
This has some reasons, let's try to sum them up:


Android has an open app market model (there's the more or less curated Play store but you can install apps from other locations (3rd party markets or self built/downloaded))
Android may also not need AntiVirus apps (most problems come from pirated rogue apps with added value piggybacked)
iOS has a strictly curated app store and you're not allowed to bypass it (unless you don't jailbreak your device but Apple so far ignores the existence of jailbroken devices)
Apple doesn't allow AntiVirus apps into their app store (they don't grant the necessary privileges to 3rd party apps and ignore the existence of jailbroken devices)
AntiVirus vendors want to create a market for mobile AntiVirus solutions
Apple denies existence/possibility of malware for their platforms as long as it's possible (for PR reasons)


To sum it up: Android is more open than iOS and lets AntiVirus vendors jump in while Apple denies them access to their app store.