我正在实现样式菜单中的幻灯片。
菜单被添加为显示时的 subview Controller ,然后以动画方式进入 View 。一旦它关闭,我就将其从 View 中删除。
我想介绍一个 UIPanGestureRecognizer
,这样用户就可以将它滑动到 View 中,但是添加 View 的逻辑只会在按下打开时触发。
我想避免在每个手势上多次添加它,所以我在考虑检查它是否存在,如果不添加,则设置动画。
惰性 var menuController = MenuController()
private var menuWidth: CGFloat = 300
private let keyWindow = UIApplication.shared.keyWindow
override func viewDidLoad() {
super.viewDidLoad()
setupNavigationItems()
setupTableView()
menuController.view.frame = CGRect(x: -menuWidth, y: 0, width: menuWidth, height: view.frame.height)
let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
view.addGestureRecognizer(panGesture)
}
@objc func handlePan(gesture: UIPanGestureRecognizer) {
let translation = gesture.translation(in: view)
let transform = CGAffineTransform(translationX: translation.x, y: 0)
menuController.view.transform = transform
navigationController?.view.transform = transform
}
@objc func handleOpen() {
keyWindow?.addSubview(menuController.view)
animateMenuController(transform: CGAffineTransform(translationX: self.menuWidth, y: 0)) { }
addChild(menuController)
}
@objc func handleHide() {
animateMenuController(transform: .identity) { [weak self] in
self?.menuController.view.removeFromSuperview()
self?.menuController.removeFromParent()
}
}
我希望做这样的事情
@objc func handlePan(gesture: UIPanGestureRecognizer) {
if view.subviews.contains(MenuController) {
print("yes")
}
let translation = gesture.translation(in: view)
let transform = CGAffineTransform(translationX: translation.x, y: 0)
menuController.view.transform = transform
navigationController?.view.transform = transform
}
但这是不正确的。
最佳答案
您可以尝试使用 vc 的 children
属性
if !children.isEmpty { // this assumes 1 vc tell if you have more
print("YES")
}
或
if let _ = children.first(where:{ $0 is menuController}) { // this assumes 1 vc tell if you have more
print("YES")
}
您可能还需要将其添加到
view.addSubview(menuController.view)
不是 keyWindow
关于ios - 如何检查 subview Controller 是否存在,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54402393/