ios - 线程 1 :EXC_BAD_INSTRUCTION(code=EXC_I386_INVOP, 子代码=0*0) 错误

我得到了错误:

1:EXC_BAD_INSTRUCTION(code=EXC_I386_INVOP,subcode=0*0)

我是编码新手，我正在关注此视频 https://www.youtube.com/watch?v=Fv-A8lKn7VY

代码如下:

import UIKit
import CoreData

class SwiftCoreDataHelper: NSObject {

    class func directoryForDatabaseFilename()->NSString{
        return NSHomeDirectory().stringByAppendingString("/Library/Private Documents")
    }

    class func databaseFilename()->NSString{
        return "database.sqlite";
    }

    class func managedObjectContext()->NSManagedObjectContext{


        do { try NSFileManager.defaultManager().createDirectoryAtPath(SwiftCoreDataHelper.directoryForDatabaseFilename() as String, withIntermediateDirectories: true, attributes: nil) }
        catch {
            print("Error Creating Directory for DB")
        }
        //        NSFileManager.defaultManager().createDirectoryAtPath(SwiftCoreDataHelper.directoryForDatabaseFilename(), withIntermediateDirectories: true, attributes: nil, error: &error)

        let path:NSString = "\(SwiftCoreDataHelper.directoryForDatabaseFilename()) + \(SwiftCoreDataHelper.databaseFilename())"

        let url:NSURL = NSURL(fileURLWithPath: path as String)

        let managedModel:NSManagedObjectModel = NSManagedObjectModel.mergedModelFromBundles(nil)!

        let storeCoordinator:NSPersistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: managedModel)

        do {
       try storeCoordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil)
        }
        catch {
            print("Error: \(error)")
            }

        let managedObjectContext = NSManagedObjectContext(concurrencyType: NSManagedObjectContextConcurrencyType.MainQueueConcurrencyType)

        managedObjectContext.persistentStoreCoordinator = storeCoordinator

        return managedObjectContext      
    }

    class func insertManagedObject(className:NSString, managedObjectConect:NSManagedObjectContext)->AnyObject{

        let managedObject:NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName(className as String, inManagedObjectContext: managedObjectConect) as NSManagedObject

        return managedObject

    }

    class func saveManagedObjectContext(managedObjectContext:NSManagedObjectContext)->Bool{
        do {
            try managedObjectContext.save()
            return true
        } catch _ {
            return false
        }
    }    

    class func fetchEntities(className:NSString, withPredicate predicate:NSPredicate?, managedObjectContext:NSManagedObjectContext)->NSArray{
        let fetchRequest:NSFetchRequest = NSFetchRequest()
        let entetyDescription:NSEntityDescription = NSEntityDescription.entityForName(className as String, inManagedObjectContext: managedObjectContext)!

        fetchRequest.entity = entetyDescription
        if (predicate != nil){
            fetchRequest.predicate = predicate!
        }

        fetchRequest.returnsObjectsAsFaults = false
        var items = NSArray()
        do { items = try managedObjectContext .executeFetchRequest(fetchRequest)
        } catch {
            print("Fetch Request Failed")
        }
        return items
    }   
}

产生错误的代码是:

let entetyDescription:NSEntityDescription = NSEntityDescription.entityForName(className as String, inManagedObjectContext: managedObjectContext)!

我无法纠正错误。

---

Best Answer-推荐答案

entityForName 返回一个可选值。它可能崩溃了，因为您使用 !

强制解包此操作的结果

在这种情况下，您可以使用 可选绑定(bind) 来测试 entityForName 是否真的返回值:

if let entityDescription = NSEntityDescription.entityForName(className as String, inManagedObjectContext: managedObjectContext) {
    // work with entityDescription
} else {
   // handle the case in which entityForName returns nil
}

关于ios - 线程 1 :EXC_BAD_INSTRUCTION(code=EXC_I386_INVOP, 子代码=0*0) 错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38956610/