College Swift Xcode game : I need help with the fact that I try to add two variables together and it says this: 
'''
Cannot convert value of type 'CGFloat' to expected argument type 'CGPoint'
'''
I would appreciate it if someone would help me to understand ow to fix this problem with my game application.
the code that has the error is: 
'''
let moveBullet = SKAction.moveTo(self.size.height + bullet.size.height, duration: 1)
'''