将代码修改为：

var newFrame = self.sliderUserInfo.frame
    newFrame.origin = self.sliderUserInfoPosition
    UIView.animateWithDuration(1, delay: 0,
        usingSpringWithDamping: springDamping,
        initialSpringVelocity: velocity, options: option!, animations: {
            self.sliderUserInfo.frame = newFrame
        }, completion: {finished  in
            if finished {
                self.loadContentView()
            }
    })

自动布局是将视图放回其所属的位置。在动画中，不要更改帧原点，而是更改视图和超级视图顶部之间的约束的约束常量。
创建一个：

var cHeight: NSLayoutConstraint!

// Start the bottom of the view off the screen
cHeight = NSLayoutConstraint(item: sliderUserInfo, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1.0, constant: -1.0)

或者从情节提要引用它：

@IBOutlet var cHeight: NSLayoutConstraint!

然后设置更改的动画：

// Animate the change of the constraint
self.cHeight.constant = self.sliderUserInfo.frame.height
// Note we animate the layoutIfneeded
UIView.animateWithDuration(1, delay: 0,
            usingSpringWithDamping: springDamping,
            initialSpringVelocity: velocity, options: option!, animations: {
                self.sliderUserInfo.layoutIfNeeded()
            }, completion: {finished  in
                if finished {
                    self.loadContentView()
                }
        })