带约束的UIViewAnimation在Swift中不起作用

我正在尝试创建一个动画，在加载父UIViewController后，我希望将uiview从右向左滑动，尽管我可以显示视图，但动画不起作用。我的动画代码：

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    view.isOpaque = false
    UIView.animate(withDuration: 1.0, delay: 1.0, options: .curveEaseOut, animations: {
        self.contentXConstraint.constant = 500
        self.contentXConstraint.constant = 80
    }) { (status) in

    }
}

我已将父视图控制器显示为显示的视图控制器：

present(navController, animated: false, completion: nil)

---

将动画代码从ViewDidDisplay移动到ViewDidLayoutSubview

您忘记了

self.view.layoutFneed（）

从

使用此方法可强制视图立即更新其布局。使用“自动布局”时，布局引擎会根据需要更新视图的位置，以满足约束中的更改

---

更新约束后，需要添加

layoutifneed（）

方法

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    view.isOpaque = false
    UIView.animate(withDuration: 1.0, delay: 1.0, options: .curveEaseOut, animations: {
        self.contentXConstraint.constant = 500
        self.contentXConstraint.constant = 80
        self.view.layoutIfNeeded()
    }) { (status) in

    }
}

---

@潘卡吉很乐意帮忙：）

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    view.isOpaque = false
    UIView.animate(withDuration: 1.0, delay: 1.0, options: .curveEaseOut, animations: {
        self.contentXConstraint.constant = 500
        self.contentXConstraint.constant = 80
        self.view.layoutIfNeeded()
    }) { (status) in

    }
}