ios - UIView 不是第一次消除

Question

我正在尝试在单击按钮时为 UIView 制作动画。它确实会在第一次点击时出现，但只有在那之后才会出现。

@IBAction func viewDetails(sender: AnyObject) {

     UIView.animateWithDuration(0.5 as NSTimeInterval, animations: {
                   println(self.viewDetailsView.center.x)
                    println(self.viewDetailsView.hidden)
                    self.viewDetailsView.hidden = false
                    self.viewDetailsView.center = CGPointMake(self.viewDetailsView.center.x - 4000, self.viewDetailsView.center.y)
                    self.view.layoutIfNeeded()
                    }, completion: {
                        finished in
                        self.detailsVisible = true
                }) }

Answer 1

试试这个:

@IBAction func viewDetails(sender: AnyObject) {

    println(self.viewDetailsView.center.x)
    println(self.viewDetailsView.hidden)
    self.viewDetailsView.hidden = false
    self.viewDetailsView.center = CGPointMake(self.viewDetailsView.center.x - 4000, self.viewDetailsView.center.y)

    UIView.animateWithDuration(0.5 as NSTimeInterval, animations: {

        self.view.layoutIfNeeded()
    }, completion: { finished in
        self.detailsVisible = true
    }) 
}