当我的应用程序进入后台(在applicationDidEnterBackground之后),出现以下警告.
2015-12-11 20:54:43.661 AppName[759:124891] *|synchronize-skip|* a fence was started inside of a snapshot block - skipping the workspace synchronize because it may dequeue messages from the fenceExemptQueue and snapshots expect that not to happen 2015-12-11 20:54:44.084 AppName[759:124891] *|synchronize-skip|* a fence was started inside of a snapshot block - skipping the workspace synchronize because it may dequeue messages from the fenceExemptQueue and snapshots expect that not to happen
我在Google上找不到任何有关信息,不知道为什么会这样.
有谁知道这是什么意思？谢谢！
解决方法
我在Swift程序中收到了同样奇怪的错误消息,最后弄清楚我的代码有什么问题.正确的代码是：
override func viewDidLoad() {
super.viewDidLoad()
let fileMgr = NSFileManager.defaultManager()
ubiquityURL = fileMgr.URLForUbiquityContainerIdentifier(nil)
guard ubiquityURL != nil else {
print("Dave: Unable to access iCloud account")
return
}
ubiquityURL = ubiquityURL?.URLByAppendingPathComponent("Documents/savefile.txt")
MetaDataQuery = NSMetadataQuery()
MetaDataQuery?.predicate = nspredicate(format: "%K like 'savefile.txt'",NSMetadataItemFSNameKey)
MetaDataQuery?.searchScopes = [NSMetadataQueryUbiquitousDocumentsScope]
NSNotificationCenter.defaultCenter().addobserver(self,selector: "MetadataQueryDidFinishGathering:",name: NSMetadataQueryDidFinishGatheringNotification,object: MetaDataQuery!)
MetaDataQuery!.startQuery()
}
在上面的代码中,正确的格式是“％K like”savefile.txt’“,但是如果您忘记了文件名中的单引号,则会收到奇怪的运行时错误消息.没有文件名的单引号,元数据查询无法在iCloud上找到您的文件.