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I'am trying to make a side menu and i have some problems with setting it with auto layout. I have a rootViewController that i add to it the leftMenuVC as childVC then i set the constraints.

class RootVC: UIViewController, NavigationBarDelegate {
    var leftMenuVC: UIViewController?
    var navigationBar = NavigationBar()
    var isMenuCollapsed = true

    override func viewDidLoad() {
        leftMenuVC = leftVC()
        addChildViewController(leftMenuVC!)
        view.addSubview(leftMenuVC!.view)
        leftMenuVC!.didMove(toParentViewController: self)
    }

    override func viewDidLayoutSubviews() {
        if let v = leftMenuVC?.view {
            v.translatesAutoresizingMaskIntoConstraints = false
            v.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
            v.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
            v.rightAnchor.constraint(equalTo: view.rightAnchor, constant: -140).isActive = true
            v.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        }
    }

    func menuButtonClicked(){

    }
}

So my question is how to change constraints to hide/show the menu with support of orientations

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2 回答 2

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与其自己编写此代码，不如为自己省去麻烦。这是MMDrawerController来拯救你。我自己正在使用它。它非常易于实施，并提供了许多自定义选项。希望你觉得它有用。:-)

于 2018-04-03T05:12:01.833 回答
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当我想用约束隐藏屏幕外的视图时，我通常会做的是：

1 设置所有约束，使侧视图可见（处于活动状态）

2 参考将侧视图固定在一侧的约束（此处为左侧）

leftAnchor = NSLayoutConstraint(item: v, attribute: .left, relatedBy: .equal, toItem: view, attribute: .left, multiplier: 1, constant: 0)
view.addConstraint(leftAnchor)
view.addConstraint(NSLayoutConstraint(item: v, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1, constant: 0))
view.addConstraint(NSLayoutConstraint(item: v, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .bottom, multiplier: 1, constant: 0))
view.addConstraint(NSLayoutConstraint(item: v, attribute: .width, relatedBy: .equal, toItem: view, attribute: .width, multiplier: 0.6, constant: 0))

3 再设置一个约束，以便隐藏视图。通常是这样的。请注意，优先级设置为 999 以避免约束冲突。

var hiddingConstraint = NSLayoutConstraint(item: v, attribute: .right, relatedBy: .equal, toItem: view, attribute: .left, multiplier: 1, constant: 0)
hiddingConstraint.priority = 999
view.addConstraint(hiddingConstraint)

4 通过激活或不激活你的 leftAnchor 来制作动画

UIView.animate(withDuration: 0.3) {
       self.leftAnchor.active = false
       self.view.layoutIfNeeded()
}

所以你最终应该得到这样的代码：

class RootVC: UIViewController, NavigationBarDelegate {
    var leftMenuVC: UIViewController?
    var navigationBar = NavigationBar()
    var isMenuCollapsed = true {
        didSet {
            UIView.animate(withDuration: 0.3) {
                self.leftAnchor?.isActive = self.isMenuCollapsed
                self.view.layoutIfNeeded()
            }
        }

    }
    var leftAnchor : NSLayoutConstraint?

    override func viewDidLoad() {
        leftMenuVC = leftVC()
        addChildViewController(leftMenuVC!)
        view.addSubview(leftMenuVC!.view)
        leftMenuVC!.didMove(toParentViewController: self)
    }

    override func viewDidLayoutSubviews() {
        if let v = leftMenuVC?.view {

            leftAnchor = NSLayoutConstraint(item: v, attribute: .left, relatedBy: .equal, toItem: view, attribute: .left, multiplier: 1, constant: 0)
            view.addConstraint(leftAnchor!)
            view.addConstraint(NSLayoutConstraint(item: v, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1, constant: 0))
            view.addConstraint(NSLayoutConstraint(item: v, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .bottom, multiplier: 1, constant: 0))
            view.addConstraint(NSLayoutConstraint(item: v, attribute: .width, relatedBy: .equal, toItem: view, attribute: .width, multiplier: 0.6, constant: 0))

            var hiddingConstraint = NSLayoutConstraint(item: v, attribute: .right, relatedBy: .equal, toItem: view, attribute: .left, multiplier: 1, constant: 0)
            hiddingConstraint.priority = 999
            view.addConstraint(hiddingConstraint)
        }
    }

    func menuButtonClicked(){
        isMenuCollapsed = !isMenuCollapsed
    }
}

PS：我不会将约束设置放在 中viewDidLayoutSubviews，也许放在 中viewWillAppear，因为您不必在每次旋转设备时都设置它们。这就是约束的目的

于 2018-03-28T23:51:38.803 回答