Question

我目前正在尝试将Core Data集成到我的项目中。起初我没有使用Core Data，但后来决定，所以我创建了一个新项目，然后将代码从AppDelegate移动到我正在处理的项目中。我的项目名称是SimpleRunner，到目前为止我只有一个实体Run。在我的SimpleRunner.xcdatamodel中，我创建了Run Entity并将其分配给我的Run类。这是Run Entity的图片，这是我将Run类分配给它pic。但是，当我尝试保存运行时，我收到以下错误：

由于未捕获的异常终止应用＆＃39; NSInvalidArgumentException＆＃39;，原因：＆＃39; - [SimpleRunner.Run setTime：]：无法识别的选择器已发送到实例。

我知道这是小事，有人请帮忙！

运行对象

import CoreData
class Run:NSManagedObject{
@NSManaged var time:String
@NSManaged var distance:String
@NSManaged var runImage:Data?
}

APP DELEGATE

// MARK: - Core Data stack

lazy var applicationDocumentsDirectory: NSURL = {
    // The directory the application uses to store the Core Data store file. This code uses a directory named "derivative.DataDemo" in the application's documents Application Support directory.
    let urls = FileManager.default().urlsForDirectory(.documentDirectory, inDomains: .userDomainMask)
    return urls[urls.count-1]
}()

lazy var managedObjectModel: NSManagedObjectModel = {
    // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
    let modelURL = Bundle.main().urlForResource("SimpleRunner", withExtension: "momd")!
    return NSManagedObjectModel(contentsOf: modelURL)!
}()

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.appendingPathComponent("SimpleRunner.sqlite")
    var failureReason = "There was an error creating or loading the application's saved data."
    do {
        try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: 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
}()

lazy var managedObjectContext: NSManagedObjectContext = {
    // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
    let coordinator = self.persistentStoreCoordinator
    var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
    managedObjectContext.persistentStoreCoordinator = coordinator
    return managedObjectContext
}()

// MARK: - Core Data Saving support

func saveContext () {
    if managedObjectContext.hasChanges {
        do {
            try managedObjectContext.save()
        } catch {
            // Replace this implementation 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.
            let nserror = error as NSError
            NSLog("Unresolved error \(nserror), \(nserror.userInfo)")
            abort()
        }
    }
}

保存运行方法中的

错误，其中run.time = time

  func saveRun(time:String,distance:String,image:UIImage){

    run = NSEntityDescription.insertNewObject(forEntityName: "Run", into: managedObjectContext) as! Run

    run.time = time <--------- WHERE THE ERROR IS
    run.distance = distance
    run.runImage = UIImagePNGRepresentation(image)

    do {
        try managedObjectContext.save()
    } catch {
        print(error)
        return
    }
}

Answer 1

您是否在模型中声明了类名？我看到你强制将NSEntityDescription.insertNewObject...的结果转换为Run（这是一件坏事，顺便说一句），如果没有正确设置类，它实际上可能是NSManagedObject

为什么这是一件坏事，你会如何实现呢？

你基本上是对编译器撒谎而不是给你的代码一个＆＃34; out＆＃34;如果你的强迫演员被证明是错的。

你最好用以下的东西：

guard let run = NSEntityDescription.insertNewObject(forEntityName: "Run", into: managedObjectContext) as? Run else { 
  //Do something here
}

甚至：

if let run = NSEntityDescription.insertNewObject(forEntityName: "Run", into: managedObjectContext) as? Run {
  //Put your logic here
}

因为这是＆＃34; Developer Error＆＃34;我会在闭包内部使用guard和fatalError。

如果你正在为iOS10开发，你可以跳过所有btw，只需使用：

let run = Run(context: managedObjectContext)

Answer 2

问题是我的xcode版本。我使用Xcode 8版本1测试版，一旦我切换到版本2它工作。自我注意：学习时使用稳定版本

使用swift的核心数据错误：[SimpleRunner.Run setTime：]：发送到实例的无法识别的选择器

2 个答案: