如何在CloudKit中删除订阅

Question

我想删除特定的订阅，但我不确定如何获得订阅ID。有几个选项可以删除订阅，所有这些都要求预先知道订阅ID：

1. 删除(带有withSubscriptionID:completionHandler：)

示例：

let database = CKContainer.default().publicCloudDatabase
database.delete(withSubscriptionID: subscription.subscriptionID) { (result, error) in
   // completed 
}

1. fetchAllSubscriptions(completionHandler:)

示例：

let database = CKContainer.default().publicCloudDatabase
database.fetchAllSubscriptions { subscriptions, error in
    if error == nil {
        if let subscriptions = subscriptions {
            // find the subscription ID of my choice and use the method from #1 to delete
        }
    } else {
        print(error!.localizedDescription)
    }
}

1. CKModifySubscriptionsOperation

示例：

let operation = CKModifySubscriptionsOperation(subscriptionsToSave: [], subscriptionIDsToDelete: [subscriptionID])
operation.modifySubscriptionsCompletionBlock =  {
    (modifiedSubscriptions: [CKSubscription]?, deletedSubscriptionIDs: [String]?, error: Error?) -> Void in

    if error != nil {
        print(error!.localizedDescription)
    } else {
        print("Success!")
    }
}
operation.qualityOfService = .utility
privateDatabase.add(operation)

为了保存和删除核心数据记录，可以使用recordName获取CKRecord ID，这在CKRecord数据中更容易保存：

let recordID = CKRecord.ID(recordName: recordName)

对于订阅是否存在类似的内容，还是在创建订阅ID时必须保存订阅ID？看起来CKQuerySubscription连recordName都没有

[<CKQuerySubscription: 0x283a3be40; ; Query Subscription: recordType=Progress, predicate=userId == "_sdfd1cedfea6965asdfdsc58e3d", subscriptionOptions=1, subscriptionID=SDF23BB6B-2C15-4F4D-BE7F-DF234GS, zoneID=(null)>
{
    alertBody -> New Post!
    alertLocalizationKey -> "(null)
    alertLocalizationArgs -> []
    title -> My App
    titleLocalizationKey -> "(null)
    titleLocalizationArgs -> []
    subtitle -> (null)
    subtitleLocalizationKey -> "(null)
    subtitleLocalizationArgs -> []
    alertActionLocalizationKey -> (null)
    alertLaunchImage -> (null)
    soundName -> default
    desiredKeys -> []
    shouldBadge -> NO
    shouldSendContentAvailable -> NO
    shouldSendMutableContent -> NO
    category -> (null)
    collapseIDKey -> (null)

}])

Answer 1

首先，如何创建CKQuerySubscription？在创建它时为它指定一个ID，这就是您知道subscriptionID是什么的方式：

let subscriptionWorkspace = CKQuerySubscription(
  recordType: "YourRecordType",
  predicate: ...,
  subscriptionID: "Your-ID-Goes-Here",
  options: [...]
)

如果要创建单个CKRecord的订阅，则可以创建如下所示的subscriptionID：

"YourRecordType|\(recordName)"

但是，通常有更好的方法使用predicate条件订阅整个记录类型，而不是一次订阅记录。

如果您需要进一步的帮助，请添加有关创建您的CKQuerySubscription的更多细节。