查询结果是否有任何限制 Cloudkit 私人默认区域？我不知道为什么我只使用以下查询收到前100条记录：
let p = NSPredicate(format: "(type == 'entered') AND (timestamp >= %@) AND (timestamp <= %@)", from, to)
let q = CKQuery(recordType: self.beaconRecordType, predicate: p)
q.sortDescriptors = [NSSortDescriptor(key: "timestamp", ascending: true)]
self.privateDatabase?.performQuery(q, inZoneWithID: nil, completionHandler: { results, error in
//count = 100
println(results.count)
}
好的。正如Edwin在答案中提到的，解决方案是使用CKQueryOperation获取初始数据块，然后使用completionBlock中的“cursor”来触发另一个操作。这是一个例子：
UPDATE
func fetchBeacons(from:NSDate, to:NSDate) {
let p = NSPredicate(value: true)
let q = CKQuery(recordType: self.beaconRecordType, predicate: p)
let queryOperation = CKQueryOperation(query: q)
queryOperation.recordFetchedBlock = fetchedARecord
queryOperation.queryCompletionBlock = { [weak self] (cursor : CKQueryCursor!, error : NSError!) in
if cursor != nil {
println("there is more data to fetch")
let newOperation = CKQueryOperation(cursor: cursor)
newOperation.recordFetchedBlock = self!.fetchedARecord
newOperation.queryCompletionBlock = queryOperation.queryCompletionBlock
self!.privateDatabase?.addOperation(newOperation)
}
}
privateDatabase?.addOperation(queryOperation)
}
var i = 0
func fetchedARecord (record: CKRecord!) {
println("\(NSDate().timeIntervalSinceReferenceDate*1000) \(++i)")
}
100是标准查询的默认限制。这个数额不固定。它可能会根据iCloud的总负载而有所不同。如果你想影响那个数量，那么你需要使用CKQueryOperation并设置resultsLimit如下：
operation.resultsLimit = CKQueryOperationMaximumResults;
CKQueryOperationMaximumResults是默认值，并将其限制为100（大部分时间）。不要将该值设置得太高。如果需要更多记录，请使用queryCompletionBlock的光标继续读取更多记录。
我在我的项目中使用此代码从记录类型中获取所有记录，它在目标c中。我根据需要使用“Entry”键。
+ (void)fetchRecordsWithType:(NSString *)recordType
completionHandler:(void (^)(NSArray *records, NSError *error))completionHandler {
NSPredicate *truePredicate = [NSPredicate predicateWithValue:YES];
CKQuery *query = [[CKQuery alloc] initWithRecordType:recordType
predicate:truePredicate];
CKQueryOperation *queryOperation = [[CKQueryOperation alloc] initWithQuery:query];
queryOperation.desiredKeys = @[@"Entry"];
NSMutableArray *results = [NSMutableArray new];
queryOperation.recordFetchedBlock = ^(CKRecord *record) {
[results addObject:record]; };
queryOperation.queryCompletionBlock = ^(CKQueryCursor *cursor, NSError *error) {
[self retrieveNextBatchOfQueryFromCursor:cursor
results:results
error:error
completionHandler:completionHandler]; };
[[self CloudKitContainer].privateCloudDatabase addOperation:queryOperation]; }
+ (void)retrieveNextBatchOfQueryFromCursor:(CKQueryCursor *)cursor
results:(NSMutableArray *)results
error:(NSError *)error
completionHandler:(void (^)(NSArray *records, NSError *error))completionHandler {
// CloudKit apparently has query limit
if (cursor != nil
&& !error) {
CKQueryOperation *nextOperation = [[CKQueryOperation alloc] initWithCursor:cursor];
nextOperation.recordFetchedBlock = ^(CKRecord *record) {
[results addObject:record]; };
nextOperation.queryCompletionBlock = ^(CKQueryCursor *cursor, NSError *error) {
[self retrieveNextBatchOfQueryFromCursor:cursor
results:results
error:error
completionHandler:completionHandler]; };
[[self CloudKitContainer].privateCloudDatabase addOperation:nextOperation]; }
else {
dispatch_async(dispatch_get_main_queue(), ^(void){
completionHandler(results, error); }); }}
在具有完成处理程序的函数内运行它的另一种方法是在获取所有记录之前不会停止。这可以由应用程序中的不同视图控制器重用。
询问
func cloudKitLoadRecords(result: (objects: [CKRecord]?, error: NSError?) -> Void){
// predicate
var predicate = NSPredicate(value: true)
// query
let cloudKitQuery = CKQuery(recordType: "ClassName", predicate: predicate)
// records to store
var records = [CKRecord]()
//operation basis
let publicDatabase = CKContainer.defaultContainer().publicCloudDatabase
// recurrent operations function
var recurrentOperationsCounter = 101
func recurrentOperations(cursor: CKQueryCursor?){
let recurrentOperation = CKQueryOperation(cursor: cursor!)
recurrentOperation.recordFetchedBlock = { (record:CKRecord!) -> Void in
print("-> cloudKitLoadRecords - recurrentOperations - fetch \(recurrentOperationsCounter++)")
records.append(record)
}
recurrentOperation.queryCompletionBlock = { (cursor:CKQueryCursor?, error:NSError?) -> Void in
if ((error) != nil)
{
print("-> cloudKitLoadRecords - recurrentOperations - error - \(error)")
result(objects: nil, error: error)
}
else
{
if cursor != nil
{
print("-> cloudKitLoadRecords - recurrentOperations - records \(records.count) - cursor \(cursor!.description)")
recurrentOperations(cursor!)
}
else
{
print("-> cloudKitLoadRecords - recurrentOperations - records \(records.count) - cursor nil - done")
result(objects: records, error: nil)
}
}
}
publicDatabase.addOperation(recurrentOperation)
}
// initial operation
var initialOperationCounter = 1
let initialOperation = CKQueryOperation(query: cloudKitQuery)
initialOperation.recordFetchedBlock = { (record:CKRecord!) -> Void in
print("-> cloudKitLoadRecords - initialOperation - fetch \(initialOperationCounter++)")
records.append(record)
}
initialOperation.queryCompletionBlock = { (cursor:CKQueryCursor?, error:NSError?) -> Void in
if ((error) != nil)
{
print("-> cloudKitLoadRecords - initialOperation - error - \(error)")
result(objects: nil, error: error)
}
else
{
if cursor != nil
{
print("-> cloudKitLoadRecords - initialOperation - records \(records.count) - cursor \(cursor!.description)")
recurrentOperations(cursor!)
}
else
{
print("-> cloudKitLoadRecords - initialOperation - records \(records.count) - cursor nil - done")
result(objects: records, error: nil)
}
}
}
publicDatabase.addOperation(initialOperation)
}
用法
cloudKitLoadRecords() { (queryObjects, error) -> Void in
dispatch_async(dispatch_get_main_queue()) {
if error != nil
{
// handle error
}
else
{
// clean objects array if you need to
self.objects.removeAll()
if queryObjects!.count == 0
{
// do nothing
}
else
{
// attach found objects to your object array
self.objects = queryObjects!
}
}
}
}
Swift最简单的例子：
func fetchServices(completion: ErrorHandler? = nil) {
var records = [CKRecord]()
let query = CKQuery(recordType: "Service", predicate: NSPredicate(value: true))
let queryOperation = CKQueryOperation(query: query)
queryOperation.recordFetchedBlock = { record in
records.append(record)
}
queryOperation.queryCompletionBlock = { cursor, error in
self.fetchServices(with: cursor, error: error, records: records, completion: completion)
}
database.add(queryOperation)
}
private func fetchServices(with cursor: CKQueryCursor?, error: Swift.Error?, records: [CKRecord], completion: ErrorHandler? = nil) {
var currentRecords = records
if let cursor = cursor, error == nil {
let queryOperation = CKQueryOperation(cursor: cursor)
queryOperation.recordFetchedBlock = { record in
currentRecords.append(record)
}
queryOperation.queryCompletionBlock = { cursor, error in
self.fetchServices(with: cursor, error: error, records: currentRecords, completion: completion)
}
database.add(queryOperation)
} else {
parseAndSaveServices(with: records, completion: completion)
}
}