Swift UICollectionView单元格。尝试设置子视图的动画

试图在集合视图单元内设置子视图的动画，但我只得到状态之间的突然变化

...

    func animate (){
    if self.signOut.hidden == false{
        UIView.animateWithDuration(0.2) {
            self.signOut.hidden = true
        }
    }else{
        UIView.animateWithDuration(0.2) {
            self.signOut.hidden = false
        }
    }

...

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非常感谢任何提示

需要减小动画块内的alpha，以便视图平滑消失

      UIView.animateWithDuration(0.33, delay: 0.0, options: [.CurveEaseInOut], animations: {
            self.signOut.alpha = 0.0
        }) { finished in
            self.signOut.hidden = true
        }

---

需要减小动画块内的alpha，视图才能平滑消失

      UIView.animateWithDuration(0.33, delay: 0.0, options: [.CurveEaseInOut], animations: {
            self.signOut.alpha = 0.0
        }) { finished in
            self.signOut.hidden = true
        }