The 18-year-old told MTV News: 'Katy Perry gave me a song called Rock God, it's one of my favourite songs ever.
'I actually had to fight for that song - I wanted it so bad.'
The Ramona and Beezus actress added: 'It's kind of funky, and I think I used her style and we kind of mixed it
up with the producers that I worked with with my style, so we made it a little bit more techno.'I just loved her style, and she did background vocals on that as well, so I was very, very blessed on the record, 'cause it's so much fun, and I can't wait to perform it.'
