[untog]

You have to use the Safari rendering engine, though - Apple will not allow any others in the App Store.

I don't think that's as big of an issue as others do, but it is still a restriction.

[saagarjha]

Which is the same one that Apple itself uses. This was an issue a couple years ago when Apple kept the fast Nitro rendering engine for itself, but now that they've provided it to everyone else I wouldn't call it anticompetitive.