情况:我想从数据条目列表导航回我的 PageViewController。
before 和 previous 函数起作用
func pageViewController(pageViewController: UIPageViewController,
viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
if ((viewController as! LocationViewController).mLocationIndex > 0){
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("LocationViewController") as! LocationViewController
vc.mLocationIndex = (viewController as! LocationViewController).mLocationIndex - 1
return vc
}
return nil
}
func pageViewController(pageViewController: UIPageViewController,
viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
let locCount = DataManager.sharedInstance.getLocationCount()
if ((viewController as! LocationViewController).mLocationIndex < locCount - 1){
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("LocationViewController") as! LocationViewController
vc.mLocationIndex = (viewController as! LocationViewController).mLocationIndex + 1
return vc
}
return nil
}
问题: 如果我在 viewDidLoad() 中设置 UIPageViewController
的 UIViewController
(Location),我可以通过 UIPageViewController
到我的 UITableView
并且我能够导航回来并且一切正常。但是我想删除我的 UITableView
中的位置,当我删除我想返回的位置时(每个位置后面都是 CoreData
中的 dada)它崩溃了,因为数据在 CoreData
中消失了。
我尝试在 viewWillAppear(animated: Bool) 中设置 UIViewController
(Location)。现在我可以删除条目,向后导航并拥有自己的设置 UIViewController
(Location) BUT - 如果我滚动到上一个 View 的“副本”尽管 viewControllerBeforeViewController
返回 nil 只是显示...这怎么可能?
第一个 viewDidLoad() 版本的代码片段:
class MainPageViewController: UIPageViewController {
override func viewDidLoad() {
super.viewDidLoad()
dataSource = self
let dM = DataManager.sharedInstance
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("LocationViewController") as! LocationViewController
dM.mActualLocationIndex = 0
// check if the index is too big (deleted data)
if (dM.mActualLocationIndex < dM.getLocationCount()){
vc.mLocationIndex = dM.mActualLocationIndex
} else {
vc.mLocationIndex = 0
dM.mActualLocationIndex = 0
}
vc.mLocationIndex = 0
setViewControllers([vc], direction: UIPageViewControllerNavigationDirection.Forward, animated: true, completion: nil)
}
override func viewWillAppear(animated: Bool) {
}
最佳答案
我找到了一个解决方案:
extension UIPageViewController {
func setViewControllerAndClearCache(vc: UIViewController){
setViewControllers([vc], direction: .Forward, animated: true, completion: { _ in
dispatch_async(dispatch_get_main_queue(), {
self.setViewControllers([vc], direction: .Forward, animated: false, completion: nil)
})
})
}
}
使用 setViewControllerAndClearCache(vc: UIViewController)
,我在 UIPageViewController
的 viewWillAppear()
中调用,我能够“清除现金 View ”,当我返回时,不再有前一个 View 的“副本”!
关于ios - 如何导航回已删除的 PageViewController 条目/更改 PageViewController 条目,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37083297/