【发布时间】：2019-09-18 07:17:57
【问题描述】：
我创建了一个UICollectionView，其中的单元格包含几种类型的UIViewController 视图作为它们的contentView。我想缓存未使用的UIViewController。我已经尝试根据他们的 indexPath 创建当前使用的UIViewController 的字典，以及一组未使用的UIViewController 要回收UIViewController 的字典。但是我注意到我的 UIViewControllers 没有被取消初始化。我的实现基于这些答案Add UIViewController to UICollectionViewCell 和Make PageViewController reuse viewControllers like tableView。
下面是我的实现
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
addViewController(toCell: cell, at: indexPath, of: viewTypes[indexPath.item])
}
func collectionView(_ collectionView: UICollectionView, didEndDisplaying cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
removeViewController(fromCell: cell, at: indexPath)
// cleanCachedViewControllers(index: indexPath.item)
}
func addViewController(toCell cell:UICollectionViewCell, at indexPath:IndexPath,of type:ViewControllerType){
var childViewController:UIViewController!
if let cvc = currentViewControllers[indexPath]{
childViewController = cvc
}else{
childViewController = TestViewController()
currentViewControllers[indexPath] = childViewController
}
self.addChild(childViewController)
childViewController.view.frame = cell.contentView.bounds
cell.contentView.addSubview(childViewController.view)
childViewController.didMove(toParent: self)
}
func removeViewController(fromCell cell:UICollectionViewCell, at indexPath:IndexPath){
guard let childViewController = currentViewControllers[indexPath] else {
return
}
print("remove view controller called")
childViewController.willMove(toParent: nil)
childViewController.view.removeFromSuperview()
childViewController.removeFromParent()
// currentViewControllers[indexPath] = nil
// currentViewControllers.removeValue(forKey: indexPath)
childViewController.view = nil
recycledViewControllers.insert(childViewController)
}
func getRecycledViewController(type:ViewControllerType)->UIViewController{
var unusedViewControllers = recycledViewControllers.filter { (viewController) -> Bool in
return viewController.isKind(of: type.type) && viewController.parent == nil
}
if let reusableViewController = unusedViewControllers.first{
recycledViewControllers.remove(reusableViewController)
return reusableViewController
}else{
let newViewController = type.initializeViewController()
// recycledViewControllers.append(newViewController)
return newViewController
}
}
【问题讨论】：
标签： ios swift caching uiviewcontroller uicollectionview