ios - 如何在Core Data中的NSFetchedResultsController中使用缓存

Question

我正在我的 viewDidLoad 方法中执行此代码

fetchedResultCont = NSFetchedResultsController(fetchRequest: req,
 managedObjectContext: container.viewContext,
 sectionNameKeyPath: nil,
 cacheName: nil)

文档说我们可以使用缓存来加快进程，但没有实现。

谁能告诉我如何使用缓存代替缓存名称中的 nil 来加快进程？

Answer 1

您只需指定一个将用作缓存目录名称的字符串。

fetchedResultCont = NSFetchedResultsController(fetchRequest: req,
     managedObjectContext: container.viewContext,
     sectionNameKeyPath: "SectionKey",
     cacheName: "MyCache")

但是，由于您没有在提取请求中使用部分，因此缓存不会给您带来好处:

来自documentation

The name of the cache file the receiver should use. Pass nil to prevent caching.

Pre-computed section info is cached to a private directory under this name. If Core Data finds a cache stored with this name, it is checked to see if it matches the fetchRequest. If it does, the cache is loaded directly—this avoids the overhead of computing the section and index information. If the cached information doesn’t match the request, the cache is deleted and recomputed when the fetch happens.