向下转发核心数据错误

Question

我正在使用核心数据，在我的AppDelegate.swift中，我在此行dict[NSUnderlyingErrorKey] = error as NSError上收到以下错误：

  

'ErrorType'不能转换为'NSError';你的意思是用'as！'迫使低垂？

以下是相应的代码：

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
    // The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
    // Create the coordinator and store
    let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("On The Go.sqlite")
    var failureReason = "There was an error creating or loading the application's saved data."
    do {
        try coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil)
    } catch {
        // Report any error we got.
        var dict = [String: AnyObject]()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason

        dict[NSUnderlyingErrorKey] = error as NSError
        let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
        // Replace this 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.
        NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
        abort()
    }

    return coordinator
}()

以下是代码的屏幕截图：

我做了错误建议的内容，但存在同样的错误。

Answer 1

如果更改catch以在NSError错误中包含模式匹配，该怎么办？

do {
} catch let e as NSError {
    // handle NSError case
} catch {
}

由于您的块现在可以抛出，您将不得不改变您的功能：

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = try? { () throws in
    // your code
}

Answer 2

尝试将catch替换为catch let error as NSError。