I haven't heard anything about this but it makes sense. Apple computers don't get viruses because no one uses them (7.7%). When it comes to electronics, which ever ones are the most common are the most attacked. I know how to hack into Coke and Pepsi machines to change prices!
iOS has about 27% of the Smartphone market which makes it the majority now thus the most vulnerable. However, due to the proprietary nature of Apple products, creating a virus/exploit will be more difficult to create. Apple will just push out an update right away to fix the problem anyway.
With other OSs, updates will be harder to push to the user because of the different hardware profiles of each device.
Also, you have to define what you consider a virus or malware: [App Tracking]