在使用UIPageViewController
的教程中,有这样的代码:
if self == parent.pages.first {
self.label_Back.isUserInteractionEnabled = false
}
基本上检查self
是否是第一个控制器堆栈。如何运作?
而且,如果我们在pages
的UIViewController
数组中有一个控制器类的多个实例,那么将firstIndex
做如下工作吗?
/**
Notifies '_tutorialDelegate' that the current page index was updated.
*/
private func notifyTutorialDelegateOfNewIndex() {
if let firstViewController = viewControllers?.first,
let index = self.pages.firstIndex(of: firstViewController) {
tutorialDelegate?.tutorialPageViewController(tutorialPageViewController: self, didUpdatePageIndex: index)
}
}
if self == parent.pages.first