nsfetchedresultscontroller 删除名称在 swift 中的缓存

Question

标题已经说明了。从 nsfetchedresultscontroller 中删除缓存的 swift 代码是什么。

这是我得到的错误：

You have illegally mutated the NSFetchedResultsController's fetch request, its predicate, or its sort descriptor without either disabling caching or using +deleteCacheWithName:'

和代码：

if arranged == "naam - A-Z" {
            let sortDescriptor = NSSortDescriptor(key: "name", ascending: true)
            self.fetchedResultsController.fetchRequest.sortDescriptors = [sortDescriptor]
        }else if arranged == "naam - Z-A" {
            let sortDescriptor = NSSortDescriptor(key: "name", ascending: false)
            self.fetchedResultsController.fetchRequest.sortDescriptors = [sortDescriptor]
        }else if arranged == "gemiddelde - 1-10" {
            let sortDescriptor = NSSortDescriptor(key: "gemiddelde", ascending: true)
            self.fetchedResultsController.fetchRequest.sortDescriptors = [sortDescriptor]
        }else if arranged == "gemiddelde - 10-1" {
            let sortDescriptor = NSSortDescriptor(key: "gemiddelde", ascending: false)
            self.fetchedResultsController.fetchRequest.sortDescriptors = [sortDescriptor]
        }

        do {
            try _fetchedResultsController!.performFetch()
        } catch {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
           // print("Unresolved error \(error), \(error.userInfo)")
            abort()
        }
        tableView.reloadData()

如果您需要更多信息，请告诉我。

更新：

我想要这样的东西：

fetchedResultsController.deleteCacheWithName("Master")

但是我不知道怎么办。

Answer 1

fetchedResultsController.deleteCacheWithName("Master")

无法编译，因为

public class func deleteCacheWithName(name: String?)

是一个类型函数，它必须在类型(class)本身上调用，不在一个实例上：

// Swift 2:
NSFetchedResultsController.deleteCacheWithName("Master")
// Swift 3:
NSFetchedResultsController<NSFetchRequestResult>.deleteCache(withName: "Master")

如果您正在使用缓存，则必须在更改任何提取请求、其谓词或其排序描述符之前清除缓存。或者，您可以创建获取的结果控制器不使用缓存：

NSFetchedResultsController(..., cacheName: nil)

nsfetchedresultscontroller 删除名称在 swift 中的缓存

nsfetchedresultscontroller delete cache with name in swift

caching

nsfetchedresultscontroller

swift