UIView.animateWithDuration(0.5, delay: 0.5, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.0, options: [], animations: {
self.loginButton.center.y -= 30.0
self.loginButton.alpha = 1.0 }, completion: nil)
UIViewAnimationOptions 空 可写成[]
多个组合 [.x,.y,.z]