在大量搜索示例代码后设法将CKFetchRecordsOperation拼凑在一起；这是...但是我一定错过了一些东西。不要误会我的意思，它可以治疗...但是...
要执行CKFetchRecordsOperation，您需要一个NSArray的CKRecordIDs。要获取CKRecordIDs的NSArray，您需要执行CKQuery，从而可以构建CKRecordIDs的NSArray。
但是请稍等，提取CKRecordID的过程使用了CKQuery，无论如何我都可以简单地下载CKRecords？
如果不使用CKQuery，如何获取CKRecordID的NSArray？
-(void)doSingleBeaconsDownload
{
CKDatabase *publicDatabase = [[CKContainer containerWithIdentifier:@"iCloud.cqd.ch.BeaconBrowser"] publicCloudDatabase];
NSPredicate *predicatex = [NSPredicate predicateWithFormat:@"iBeaconConfig = %@",iBeaconsConfirmed.giReferenceID];
CKQuery *query = [[CKQuery alloc] initWithRecordType:@"Running" predicate:predicatex];
[self.delegate performSelectorOnMainThread:@selector(processCompleted:) withObject:@"Downloading Configuration ..." waitUntilDone:YES];
[publicDatabase performQuery:query inZoneWithID:nil completionHandler:^(NSArray *results, NSError *error) {
if (error) {
NSLog(@"Batch Download Error iCloud error %@",error);
}
else {
NSMutableArray *rex2download = [[NSMutableArray alloc] init];
for (CKRecord *rex in results) {
[rex2download addObject:rex.recordID];
}
CKFetchRecordsOperation *fetchRecordsOperation = [[CKFetchRecordsOperation alloc] initWithRecordIDs:rex2download];
/* fetchRecordsOperation.perRecordCompletionBlock = ^(CKRecord *record, CKRecordID *recordID, NSError *error) {
if (error) {
// Retain the record IDs for failed fetches
}
else {
// Do something with each record downloaded
}
};*/
fetchRecordsOperation.perRecordProgressBlock = ^(CKRecordID *record, double recordsDownloaded) {
if (error) {
// damn ...
} else {
NSLog(@"Downloaded %f", recordsDownloaded);
}
};
fetchRecordsOperation.fetchRecordsCompletionBlock = ^(NSDictionary *recordsByRecordID, NSError *error) {
if (error) {
// Failed to fetch all or some of the records
}
else {
for(CKRecord *record in results) {
NSLog(@"Fini download %lu",(unsigned long)[recordsByRecordID count]);
}
[self.delegate performSelectorOnMainThread:@selector(beaconsDownloaded:) withObject:noOf waitUntilDone:YES];
}
};
[publicDatabase addOperation:fetchRecordsOperation];
}
}];
}
最佳答案
从Apple Documentation:CKFetchRecordsOperation对象从iCloud检索CKRecord对象(您已经知道其ID)。
CKQueryOperation用于基于某些查询从iCloud检索CKRecord，因此即使您不知道它们的recordID，也可以获取它们。仅当您具有CKRecordID时，才使用CKFetchRecordsOperation。您可以创建CKRecordID而不访问iCloud，并且可以将它们存储在您拥有的任何本地存储中。
我用于这种操作的一个很好的用例是，当您想修改CKRecord时，需要首先从iCloud中检索它(使用CKFetchRecordsOperation)，然后再使用CKModifyRecordsOperation将其保存回来。
看看CloudKit上的两个WWDC 2014视频，它们很好地解释了这一点。