Question

 func read()
 {
    let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

    let managedContext = appDelegate.managedObjectContext!

    let fetchRequest = NSFetchRequest(entityName: "Coupons")

    var error: NSError?

    let sortDescriptor = NSSortDescriptor(key: "coupon_id", ascending: true)

    // Set the list of sort descriptors in the fetch request,
    // so it includes the sort descriptor

    fetchRequest.sortDescriptors = [sortDescriptor]
    for var i = 0; i < fetch_coupon_category.count ; i++ {

    //condition like here.
    let predicate1 = NSPredicate(format: "coupon_categories == %@", fetch_coupon_category[i])

 // Set the predicate on the fetch request
// Combine the two predicates above in to one compound predicate
//let the predicate on the fetch request

    fetchRequest.predicate = predicate1

我正在尝试将此代码转换为swift2，尝试捕获功能

        do{
            let fetchedResults = try managedObjectContext.executeFetchRequest(fetchRequest)
                as? [NSManagedObject]?

                if let results = fetchedResults {

                for (var i=0; i < results.count; i++) {

                    let single_result = results[i]

                    let out = single_result.valueForKey("coupon_name") as! String
                    tickets.append(single_result)

                }

            }
            else
            {
                print("cannot read")
            }
        }catch let fetchError as NSError{

            print("fetching error: \(fetchError.localizedDescription)")
           // return nil

        }

    }

}

我在管理中遇到错误

'try managedObjectContext'使用未解析的标识符

如何将我的代码转换为swift 2.0，从而在转换代码时出现更多错误-.-

Answer 1

使用try managedContext代替try managedObjectContext，因为实际上您已将managedObjectContext的值分配到当前viewcontroller中的managedContext

转换为swift 2.0在managedObjectContext中出错

1 个答案: