Question

因此，将我的代码迁移到Swift 3让我有点卡住了。现在似乎NSBatchDeleteRequest需要iOS 10？我可以进行代码构建的唯一方法是使用以下代码段：

func removeAllChargerData(){
    // Remove all charging data from persistent storage
    let fetchRequest: NSFetchRequest<NSFetchRequestResult> = ChargerPrimary.fetchRequest()
    let entity = NSEntityDescription.entity(forEntityName: "ChargerPrimary", in: self.secondMoc)
    fetchRequest.entity = entity
    let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)

    do {
        try self.secondMoc.execute(deleteRequest)
    } catch {
        let deleteError = error as NSError
        NSLog("\(deleteError), \(deleteError.localizedDescription)")
    }

}

但是，会出现一条警告，表示fetchRequest()仅在iOS 10及更新版本中可用。如果我按以下方式定义fetchRequest，则会收到错误，因为它期望fetchRequest具有NSFetchRequestResult参数类型：

let fetchRequest = NSFetchRequest<ChargerPrimary>(entityName: "ChargerPrimary")

Answer 1

您只需要为通用指定正确的类型：

let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "ChargerPrimary")

Answer 2

可能它在IOS 10中也适合我

 let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "ChargerPrimary")
 let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)

你应该像这样使用fetchrequest而不给varible

特定的类型

对于IOS 9，这是DEMO

仅适用于iOS 10的Swift 3中的NSBatchDeleteRequest？

2 个答案: