The curtain has been dropped. The lineup of the 2014 I Heart Music Festival in Vegas. Is now visible for the world to see. Fronting the annual two day event. Taylor Swift, Coldplay, Usher, Ariana Grande, Nicki Minaj, Motley Crue, Paramore, One Direction, Train, Iggy Azalea, Eric Church, Lorde, Calvin Harris, Bastille, Zac Brown Band and Ed Sheeran are among the headliners for Clear Channel's 4th annual iHeartRadio Music Festival. The event is scheduled for September 19 and 20 at MGM Grand in Las Vegas.