Ios UINavigationControllerDelegate方法调用两次
我已经建立了一个非常简单的项目，没有故事板，一个窗口和一个UINavigationController，其中包含一个普通的老UIViewController作为rootViewController。在AppDelegate中，我已将UINavigationController的委托设置为self并实现Ios UINavigationControllerDelegate方法调用两次,ios,iphone,swift,uiviewcontroller,uinavigationcontroller,Ios,Iphone,Swift,Uiviewcontroller,Uinavigationcontroller,我已经建立了一个非常简单的项目，没有故事板，一个窗口和一个UINavigationController，其中包含一个普通的老UIViewController作为rootViewController。在AppDelegate中，我已将UINavigationController的委托设置为self并实现 navigationController:didShowViewController:animated包含一行： NSLog（“显示视图控制器”） 当我启动我的应用程序时，UINavigation
navigationController:didShowViewController:animatedNSLog（“显示视图控制器”）navigationController:didShowViewController:animated经过实验，我发现iOS 13使UITabBarController中第一个UINavigationController的问题变得更加复杂 不会为调用堆栈调用第一个UINavigationController
[UINavigationController ViewDidDisplay://代码>
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.delegate = self
}
}
extension ViewController: UINavigationControllerDelegate {
func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
print("willShow")
}
func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
print("didShow")
}
}
输出将是
willShow
didShow -> this one is from call stack `[UINavigationController __viewWillLayoutSubviews]`
对于第一个选项卡
这意味着，如果您使用的是iOS 13下面的旧解决方案，那么第一次显示first VC时，将不会调用first VC的didShow
我能想到的新解决方法仍然是在viewDidLoad
中设置委托，但尝试停止对VC的第一次调用，而不是在TabBarVC中的第一次调用
将按此顺序调用didShow
LAUNCH APP
VC1 willShow
VC1 didShow `[UINavigationController __viewWillLayoutSubviews]`
SELECT SECOND TAB
VC2 willShow
VC2 didShow `[UINavigationController __viewWillLayoutSubviews]`
VC2 didShow `[UINavigationController viewDidAppear:]` -> this is the one I try to get rid off
SELECT BACK TO FIRST TAB
VC1 willShow
VC1 didShow `[UINavigationController viewDidAppear:]`
SELECT BACK TO SECOND TAB
VC2 willShow
VC2 didShow `[UINavigationController viewDidAppear:]`
因此，设置一个标志，以使第一次调用UINavigationController'didShow低于iOS 13 如果你只需要
func-navigationController（\unavigationcontroller:UINavigationController，didShow-viewController:UIViewController，animated:Bool）class ViewController: UIViewController {
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
navigationController?.delegate = self
}
}
extension ViewController: UINavigationControllerDelegate {
func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
// do something
}
}
class NavigationController: UINavigationController {
override func viewDidAppear(_ animated: Bool) {
delegate = self
super.viewDidAppear(animated)
}
}
extension NavigationController: UINavigationControllerDelegate {
func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
print("will")
}
func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
print("did")
}
}
func-navigationController（\unavigationcontroller:UINavigationController，willShow-viewController:UIViewController，animated:Bool）ViewController将正常调用showdidShowclass ViewController: UIViewController {
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
navigationController?.delegate = self
}
}
extension ViewController: UINavigationControllerDelegate {
func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
// do something
}
}
class NavigationController: UINavigationController {
override func viewDidAppear(_ animated: Bool) {
delegate = self
super.viewDidAppear(animated)
}
}
extension NavigationController: UINavigationControllerDelegate {
func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
print("will")
}
func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
print("did")
}
}
由于
didShowsuper.viewdidsearch（动画）