Question

我正面临这个问题

“ NSBatchDeleteRequest”仅在iOS 9.0或更高版本上可用

class func delete(placeId:Int64) {
        let context = CoreDataStack.getContext()
        let fetch = NSFetchRequest<NSFetchRequestResult>(entityName: "Place")
        fetch.predicate = NSPredicate(format: "id = \(placeId)")
        let request = NSBatchDeleteRequest(fetchRequest: fetch)

        do {
            _ = try context.execute(request)
        } catch {
            fatalError("Failed to execute request: \(error)")
        }
        CoreDataStack.saveContext()
    }

iOS 9之前用于相同功能的代码是什么？

Answer 1

只是一个循环，获取记录并将其删除

let context = CoreDataStack.getContext()
let fetch = NSFetchRequest<NSFetchRequestResult>(entityName: "Place")
fetch.predicate = NSPredicate(format: "id = \(placeId)")
let fetchResults = try context.fetch(request)
for anItem in fetchResults {
    context.delete(anItem)
}

您可以添加此if子句以同时考虑两种方式

if #available(iOS 9, macOS 10.11, *) {

Answer 2

在iOS 9之前，您必须获取实体的每条记录并将其标记为删除，然后保存更改。

类似这样的东西：

context.performBlockAndWait
{

  if let result = try? context.fetch(fetch) 
  {
     for object in result
     {
        context.delete(object)
     } 
  }

  do 
  {
    // After mark to delete you must save the context
    try context.save()
  } 
  catch 
  {
    // Error
  }

}

感谢user1046037的帮助。

“ NSBatchDeleteRequest”仅在iOS 9.0或更高版本上可用

2 个答案: