我正在使用 CoreData 处理现有项目，该项目:

从 Web 服务接收到来自不同 CoreData 实体类型的许多项目后，它会阻塞 UI 线程很多秒，即使我在另一个线程中使用它也是如此。

请帮帮我，在项目即将完成时，有什么方法可以防止 CoreData 以最少的更改阻塞 UI？

我是 CoreData 的新手，不幸的是我没有足够的时间来研究文档或重新编程源代码。

我的数据 Controller :

class DataController {

var managedObjectContext: NSManagedObjectContext
let modelName = "something"


init(closure:()->()) {

    guard let modelURL = NSBundle.mainBundle().URLForResource(modelName, withExtension: "momd"),
        let managedObjectModel = NSManagedObjectModel.init(contentsOfURL: modelURL)
        else {
            fatalError("DataController - COULD NOT INIT MANAGED OBJECT MODEL")
    }

    let coordinator = NSPersistentStoreCoordinator.init(managedObjectModel: managedObjectModel)

    managedObjectContext = {
        let parentContext = NSManagedObjectContext(concurrencyType: .PrivateQueueConcurrencyType)
        parentContext.persistentStoreCoordinator = coordinator

        let managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
        managedObjectContext.parentContext = parentContext
        return managedObjectContext
    }()

    dispatch_async(dispatch_get_global_queue(Int(QOS_CLASS_USER_INITIATED.rawValue), 0)) {

        let options = [
            NSMigratePersistentStoresAutomaticallyOption: true,
            NSInferMappingModelAutomaticallyOption: true,
            NSSQLitePragmasOption: ["journal_mode": "DELETE"]
        ]

        let documentsURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).last
        let storeURL = NSURL.init(string: "something", relativeToURL: documentsURL)


        do {
            try coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: storeURL, options: options)

            dispatch_async(dispatch_get_main_queue()) {
                closure()
            }
        }
        catch let error as NSError {
            fatalError("DataController - COULD NOT INIT SQLITE STORE: \(error.localizedDescription)")
        }
    }
}

func save(moc: NSManagedObjectContext? = nil) {

    var managedObjectContext = moc

    if moc == nil {
        managedObjectContext = self.managedObjectContext
    }

    managedObjectContext!.performBlockAndWait {

        if managedObjectContext!.hasChanges {

            do {
                try managedObjectContext!.save()
            } catch {
                print("ERROR saving context \(managedObjectContext!.description) - \(error)")
            }
        }

        if let parentContext = managedObjectContext!.parentContext {
            self.save(parentContext)
        }
    }
}


}

我的类(class)是这样的:

class MOCity: NSManagedObject {

@NSManaged var id: NSNumber?
@NSManaged var name: String?

// Insert code here to add functionality to your managed object subclass
class func save(id: NSNumber, json: JSON, managedObjectContext: NSManagedObjectContext) {

    guard let newObject = MOCity.getById(id, create: true, managedObjectContext: managedObjectContext) else {
        fatalError("City - NO OBJECT")
    }

    newObject.id                <-- json["Id"]
    newObject.name              <-- json["Name"]

}

internal class func getById(id: NSNumber, create: Bool = false, managedObjectContext: NSManagedObjectContext) -> MOCity? {

    let fetchRequest = NSFetchRequest(entityName: "City")
    fetchRequest.predicate = NSPredicate(format: "id = \(id)")

    do {
        guard let fetchResults = try managedObjectContext.executeFetchRequest(fetchRequest) as? [MOCity] else {
            fatalError("city - NO FETCH RESULTS")
        }

        if fetchResults.count > 0 {
            return fetchResults.last
        }
        else if fetchResults.count == 0 {

            if create {
                guard let object = NSEntityDescription.insertNewObjectForEntityForName("City", inManagedObjectContext: managedObjectContext) as? MOCity else {
                    fatalError("getCity - COULD NOT CREATE OBJECT")
                }
                return object
            } else {
                return nil
            }
        }
    }
    catch let error as NSError {
    ...
    }

    return nil
}
}

还有我的网络服务类:

Alamofire.request(.POST, url,parameters:data).validate().responseJSON(completionHandler: {response in

        switch response.result {

        case .Success:

            if let jsonData = response.result.value {

                if let array = jsonData as? NSArray {

                for arrayItem in array {
                    MOCity.save(arrayItem["Id"] as! NSNumber, json: JSON(arrayItem as! NSDictionary)!, managedObjectContext: self.dataController.managedObjectContext)
                }

                self.dataController.save()

                }

            }
            break
        case .Failure(let error):
        ...                
        }


    })

最佳答案

其中一个问题可能与 QOS 级别有关。

QOS_CLASS_USER_INITIATED: The user initiated class represents tasks that are initiated from the UI and can be performed asynchronously. It should be used when the user is waiting for immediate results, and for tasks required to continue user interaction.

尝试使用QOS_CLASS_BACKGROUND。

关于ios - CoreData 阻塞 UI，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39509094/