ios - CKFetchRecordChangesOperation-更多即将到来

Question

changesOperation.fetchRecordChangesCompletionBlock = ^(CKServerChangeToken *serverChangeToken, NSData *clientChangeTokenData, NSError *operationError){

    //encode and save token

    NSData *encodedServerChangeToken = [NSKeyedArchiver archivedDataWithRootObject:serverChangeToken];

    [[NSUserDefaults standardUserDefaults] setObject:encodedServerChangeToken forKey:fetchToken];

    [[NSUserDefaults standardUserDefaults] synchronize];



    //handle more - **this causes a retain cycle**
    if(changesOperation.moreComing){

    }

};

你好，只是想知道 fetchRecordChangesCompletionBlock，文档说:

If the server is unable to deliver all of the changed results with this operation object, it sets this property to YES before executing the block in the fetchRecordChangesCompletionBlock property. To fetch the remaining changes, create a new CKFetchRecordChangesOperation object using the change token returned by the server.

在上面的代码中，这会导致保留循环，那么应该如何处理这个问题，以及在重新创建操作时是否可以使用已经创建的相同完成 block ？

Answer 1

你应该像这样定义一个弱更改操作

__weak CKFetchNotificationChangesOperation *weakChangesOperation = changesOperation;
changesOperation.fetchRecordChangesCompletionBlock = ^(CKServerChangeToken *serverChangeToken, NSData *clientChangeTokenData, NSError *operationError){
    ...
    if(weakChangesOperation.moreComing){
    }