spring动画(swift)

by 伍雪颖

loginButton.center.y+= 30
loginButton.alpha= 0
UIView.animateWithDuration(1, delay: 0.5,
    usingSpringWithDamping: 0.5,
    initialSpringVelocity: 0,
    options: .AllowUserInteraction,
    animations: {
    self.loginButton.center.y-= 30
    self.loginButton.alpha= 1

    }, completion:nil)