CloudKit-如何取消正在进行的保存/上载操作

是否有办法取消正在进行的CloudKit保存或上载操作?

time-out 情况我注意到上传视频需要一些时间,用户可能会决定解雇vc。如果他们这样做,我想取消当前的上传。

let database = CKContainer.default().publicCloudDatabase

var operation: CKModifyRecordsOperation?

func save(videoURL: URL) {

    let record = CKRecord(recordType: "MyType")
    let fileURL = URL(fileURLWithPath: videoURL.path)
    let asset = CKAsset(fileURL: fileURL)
    record["videoAsset"] = asset

    database.save(record) { (record, err) in
    }

    // or

    operation = CKModifyRecordsOperation(recordsToSave: [record], recordIDsToDelete: nil)
    operation?.savePolicy = .allKeys
    operation?.modifyRecordsCompletionBlock = { (savedRecordIDs, deletedRecordsIDs, error) in
    }

    database.add(operation!)
}