处理CloudKit错误

Question

我正在寻找有关在Swift中处理CloudKit错误的一般建议,并且无法在线查找好的示例.以下是我想知道的事情:

1)每次出现错误的可能性时,我是否应该考虑每种错误类型,或者这是不是真的有必要？

2)我已经读过处理CloudKit错误的一种常见方法是在错误消息提供的时间间隔之后重试执行操作.这种重试基本上应该是我所有错误的标准程序吗？

3)不同的CloudKit操作(保存,获取等)是否会产生不同类型的错误,或者是否存在一组标准的CloudKit错误？

提前致谢!我只是在寻找有关如何使用CloudKit处理错误处理的一般信息,因为我不确定从哪里开始.

Answer 1

我编写了一个CloudKit帮助,可以更轻松地处理错误.这只是一个起点,还有很多可以做的事情.

在当前状态下,此帮助程序的主要关注点是可以轻松地重试在适当的超时后应该重试的错误.

但是您仍然需要处理不应该重试的错误,例如用户的iCloud存储已满.即使使用此帮助程序,对这些帮助程序方法之一的每次调用都需要正确处理结果,并可能向用户报告错误.当然,您可以添加一个帮助方法来检查所有可能的错误类型并显示相应的消息.然后CloudKit代码的所有使用都可以调用那个辅助方法.

这也仅涵盖了一些可能的操作.您还希望为其他操作添加支持.最后,这还没有处理部分错误.这将是另一个有用的增强.

import Foundation
import CloudKit

public class CloudKitHelper {
    private static func determineRetry(error: Error) -> Double? {
        if let ckerror = error as? CKError {
            switch ckerror {
            case CKError.requestRateLimited, CKError.serviceUnavailable, CKError.zoneBusy, CKError.networkFailure:
                let retry = ckerror.retryAfterSeconds ?? 3.0

                return retry
            default:
                return nil
            }
        } else {
            let nserror = error as NSError
            if nserror.domain == NSCocoaErrorDomain {
                if nserror.code == 4097 {
                    print("cloudd is dead")

                    return 6.0
                }
            }

            print("Unexpected error: \(error)")
        }

        return nil
    }

    public static func modifyRecordZonesOperation(database: CKDatabase, recordZonesToSave: [CKRecordZone]?, recordZoneIDsToDelete: [CKRecordZoneID]?, modifyRecordZonesCompletionBlock: @escaping (([CKRecordZone]?, [CKRecordZoneID]?, Error?) -> Void)) {
        let op = CKModifyRecordZonesOperation(recordZonesToSave: recordZonesToSave, recordZoneIDsToDelete: recordZoneIDsToDelete)
        op.modifyRecordZonesCompletionBlock = { (savedRecordZones: [CKRecordZone]?, deletedRecordZoneIDs: [CKRecordZoneID]?, error: Error?) -> Void in
            if let error = error {
                if let delay = determineRetry(error: error) {
                    DispatchQueue.global().asyncAfter(deadline: .now() + delay) {
                        CloudKitHelper.modifyRecordZonesOperation(database: database, recordZonesToSave: recordZonesToSave, recordZoneIDsToDelete: recordZoneIDsToDelete, modifyRecordZonesCompletionBlock: modifyRecordZonesCompletionBlock)
                    }
                } else {
                    modifyRecordZonesCompletionBlock(savedRecordZones, deletedRecordZoneIDs, error)
                }
            } else {
                modifyRecordZonesCompletionBlock(savedRecordZones, deletedRecordZoneIDs, error)
            }
        }
        database.add(op)
    }

    public static func modifyRecords(database: CKDatabase, records: [CKRecord], completion: @escaping (([CKRecord]?, Error?) -> Void)) {
        CloudKitHelper.modifyAndDeleteRecords(database: database, records: records, recordIDs: nil) { (savedRecords, deletedRecords, error) in
            completion(savedRecords, error)
        }
    }

    public static func deleteRecords(database: CKDatabase, recordIDs: [CKRecordID], completion: @escaping (([CKRecordID]?, Error?) -> Void)) {
        CloudKitHelper.modifyAndDeleteRecords(database: database, records: nil, recordIDs: recordIDs) { (savedRecords, deletedRecords, error) in
            completion(deletedRecords, error)
        }
    }

    public static func modifyAndDeleteRecords(database: CKDatabase, records: [CKRecord]?, recordIDs: [CKRecordID]?, completion: @escaping (([CKRecord]?, [CKRecordID]?, Error?) -> Void)) {
        let op = CKModifyRecordsOperation(recordsToSave: records, recordIDsToDelete: recordIDs)
        op.savePolicy = .allKeys
        op.modifyRecordsCompletionBlock = { (savedRecords: [CKRecord]?, deletedRecordIDs: [CKRecordID]?, error: Error?) -> Void in
            if let error = error {
                if let delay = determineRetry(error: error) {
                    DispatchQueue.global().asyncAfter(deadline: .now() + delay) {
                        CloudKitHelper.modifyAndDeleteRecords(database: database, records: records, recordIDs: recordIDs, completion: completion)
                    }
                } else {
                    completion(savedRecords, deletedRecordIDs, error)
                }
            } else {
                completion(savedRecords, deletedRecordIDs, error)
            }
        }
        database.add(op)
    }
}

Answer 2

是的，您想检查每个cloudkit调用是否有错误。苹果在与Cloudkit相关的WWDC视频中强调了这一点。

当检测到错误时，您所做的工作差别很大。重试有时是一个选择，但有时不合适。如果使用批处理操作，则重试可能需要一些额外的工作才能提取出失败的记录。因此，是的，您有时可能想重试，但是不，您可能不会自动重试所有失败的操作。

在中定义了一组错误CKError.h。但是，您并不总是得到CKError。有时，尤其是使用CKErrorPartialFailure，您会得到一个顶层错误，其中包含嵌套错误，这些错误也必须解开。从IOS 10开始，错误列表CKError.h如下所示：

typedef NS_ENUM(NSInteger, CKErrorCode) {
    CKErrorInternalError                  = 1,  /* CloudKit.framework encountered an error.  This is a non-recoverable error. */
    CKErrorPartialFailure                 = 2,  /* Some items failed, but the operation succeeded overall. Check CKPartialErrorsByItemIDKey in the userInfo dictionary for more details. */
    CKErrorNetworkUnavailable             = 3,  /* Network not available */
    CKErrorNetworkFailure                 = 4,  /* Network error (available but CFNetwork gave us an error) */
    CKErrorBadContainer                   = 5,  /* Un-provisioned or unauthorized container. Try provisioning the container before retrying the operation. */
    CKErrorServiceUnavailable             = 6,  /* Service unavailable */
    CKErrorRequestRateLimited             = 7,  /* Client is being rate limited */
    CKErrorMissingEntitlement             = 8,  /* Missing entitlement */
    CKErrorNotAuthenticated               = 9,  /* Not authenticated (writing without being logged in, no user record) */
    CKErrorPermissionFailure              = 10, /* Access failure (save, fetch, or shareAccept) */
    CKErrorUnknownItem                    = 11, /* Record does not exist */
    CKErrorInvalidArguments               = 12, /* Bad client request (bad record graph, malformed predicate) */
    CKErrorResultsTruncated NS_DEPRECATED(10_10, 10_12, 8_0, 10_0, "Will not be returned") = 13,
    CKErrorServerRecordChanged            = 14, /* The record was rejected because the version on the server was different */
    CKErrorServerRejectedRequest          = 15, /* The server rejected this request.  This is a non-recoverable error */
    CKErrorAssetFileNotFound              = 16, /* Asset file was not found */
    CKErrorAssetFileModified              = 17, /* Asset file content was modified while being saved */
    CKErrorIncompatibleVersion            = 18, /* App version is less than the minimum allowed version */
    CKErrorConstraintViolation            = 19, /* The server rejected the request because there was a conflict with a unique field. */
    CKErrorOperationCancelled             = 20, /* A CKOperation was explicitly cancelled */
    CKErrorChangeTokenExpired             = 21, /* The previousServerChangeToken value is too old and the client must re-sync from scratch */
    CKErrorBatchRequestFailed             = 22, /* One of the items in this batch operation failed in a zone with atomic updates, so the entire batch was rejected. */
    CKErrorZoneBusy                       = 23, /* The server is too busy to handle this zone operation. Try the operation again in a few seconds. */
    CKErrorBadDatabase                    = 24, /* Operation could not be completed on the given database. Likely caused by attempting to modify zones in the public database. */
    CKErrorQuotaExceeded                  = 25, /* Saving a record would exceed quota */
    CKErrorZoneNotFound                   = 26, /* The specified zone does not exist on the server */
    CKErrorLimitExceeded                  = 27, /* The request to the server was too large. Retry this request as a smaller batch. */
    CKErrorUserDeletedZone                = 28, /* The user deleted this zone through the settings UI. Your client should either remove its local data or prompt the user before attempting to re-upload any data to this zone. */
    CKErrorTooManyParticipants            NS_AVAILABLE(10_12, 10_0) = 29, /* A share cannot be saved because there are too many participants attached to the share */
    CKErrorAlreadyShared                  NS_AVAILABLE(10_12, 10_0) = 30, /* A record/share cannot be saved, doing so would cause a hierarchy of records to exist in multiple shares */
    CKErrorReferenceViolation             NS_AVAILABLE(10_12, 10_0) = 31, /* The target of a record's parent or share reference was not found */
    CKErrorManagedAccountRestricted       NS_AVAILABLE(10_12, 10_0) = 32, /* Request was rejected due to a managed account restriction */
    CKErrorParticipantMayNeedVerification NS_AVAILABLE(10_12, 10_0) = 33, /* Share Metadata cannot be determined, because the user is not a member of the share.  There are invited participants on the share with email addresses or phone numbers not associated with any iCloud account. The user may be able to join the share if they can associate one of those email addresses or phone numbers with their iCloud account via the system Share Accept UI. Call UIApplication's openURL on this share URL to have the user attempt to verify their information. */
} NS_ENUM_AVAILABLE(10_10, 8_0);

在开发和测试应用程序时，一种方法是检查每个cloudkit操作是否有错误，如果检测到错误，则启动NSAssert来停止应用程序。然后，检查错误，潜在的错误和上下文，以确定失败的原因以及您需要采取的措施。随着时间的流逝，很可能会看到常见的模式出现，然后可以考虑构建通用的错误处理程序。