向下转换核心数据错误

Question

我使用的核心数据，并在我的AppDelegate.swift，我就在这行dict[NSUnderlyingErrorKey] = error as NSError以下错误：

“错误类型”是无法转换为“NSError”;你的意思是使用'as！'强迫低调？

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 
}() 

这里是代码的截图：

我做了错误的建议，但存在着同样的错误。

Answer 1

如果你改变你的catch来包含NSError错误的模式匹配，该怎么办？

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

由于您现在块可以抛出，你将不得不改变你的函数是这样的：

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

Answer 2

尝试用catch let error as NSError更换catch。