ios - 其值在 block 内赋值的引用变量

Question

您好，对于分配给完成 block 内的外部 ref 变量的值的范围是什么感到困惑。例如，在下面的代码中，操作错误和保存记录的值将在完成 block 之外保留。

    func applyLocalChangesToServer(insertedOrUpdatedCKRecords:Array<CKRecord>,deletedCKRecordIDs:Array<CKRecordID>) throws
    {
        var savedRecords:[CKRecord]?
        var conflictedRecords:[CKRecord] = [CKRecord]()
        var removeRecords:[CKRecord] = [CKRecord]()
        var operationError : NSError?

        let ckModifyRecordsOperation = CKModifyRecordsOperation(recordsToSave:insertedOrUpdatedCKRecords, recordIDsToDelete: deletedCKRecordIDs);
        ckModifyRecordsOperation.atomic = true
        ckModifyRecordsOperation.modifyRecordsCompletionBlock = ({(savedRecords1,deletedRecordIDs1,error)->Void in

            operationError = error

            if error == nil
            {
                wasSuccessful = true
                savedRecords = savedRecords1
            }
            else
            {
                wasSuccessful = false
                savedRecords = nil
                errorCKS = self.handleError(error!)
            }

        })
        ckModifyRecordsOperation.perRecordCompletionBlock = ({(ckRecord,error)->Void in

            if error != nil
            {  
                if error!.code == CKErrorCode.ServerRecordChanged.rawValue
                {
                    conflictedRecords.append(ckRecord!)
                }
            }

        })

        self.operationQueue?.addOperation(ckModifyRecordsOperation)
        self.operationQueue?.waitUntilAllOperationsAreFinished()

        if conflictedRecords.count > 0  
        {
            //Do work here

        }
        else if operationError != nil //Other then the partial error
        {
            throw operationError
        }

}

注意:有分配操作错误，因为 func applyLocalChangesToServer 抛出错误并且位于 while 循环内。

Answer 1

您的假设是正确的，在执行完成处理程序后，这些在封装范围内定义的变量将被修改。所以您的代码应该按预期工作。

您还可以使用以下内容:

ckModifyRecordsOperation.main()

而不是:

self.operationQueue?.addOperation(ckModifyRecordsOperation)
self.operationQueue?.waitUntilAllOperationsAreFinished()

希望有帮助。