好的,所以我在CloudKit之上构建游戏,我想查询排名前50位的用户.
// Create a CKQuery
let predicate = nspredicate(value: true)
let sortDescriptor = NSSortDescriptor(key: "score",ascending: false)
var query = CKQuery(recordtype: "Users",predicate: predicate)
query.sortDescriptors = [sortDescriptor]
// Create a query operation
var queryOperation = CKQueryOperation(query: query)
queryOperation.resultsLimit = 50
queryOperation.recordFetchedBlock = { (record: CKRecord!) -> Void in
self.records.append(record)
}
queryOperation.queryCompletionBlock = { (cursor: CKQueryCursor!,error: NSError!) in
// Log an error and show and alert
if error != nil {
println("Error querying for leaderboard: \(error)")
var alert = UIAlertController(title: "Unable Donwload leaderboard",message: "Unable to download the leaderboard at this time. Please try agin later.",preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "OK",style: UIAlertActionStyle.Default,handler: nil))
self.presentViewController(alert,animated: true,completion: nil)
return
}
// Update the records array and refresh the table view
dispatch_async(dispatch_get_main_queue(),{ () -> Void in
self.tableView.reloadData()
})
}
// Start the operation
database.addOperation(queryOperation)
这不会向记录数组添加任何记录,并在完成块中返回此错误：
<ckerror 0x1553cc10: "Permission Failure" (10/2007); server message = "Can't query system types"; uuid = 3349514B-02EC-40D7-B716-585D4ADD3128; container ID = "iCloud.com.MyCompany.MyApp">
解决方法
我在Apple的文档中找到了这个答案.特别是
CKQueries.上的文档
在讨论initWithrecordtype时：谓词：是说：
You cannot query for user records and executing a query where the record type is set to CKrecordtypeUserRecord results in an error. You must fetch user records directly using their ID.
所以我猜CloudKit不允许你查询用户记录.
我最后添加了一个得分记录,其中包含对用户的引用.我查询了然后我可以通过他们的ID获取用户.