ios - How to copy file in iCloud to app sandbox using File Manager -

i have file in cloud 15.2 kb. cannot copy app sandbox. code listed below. appreciated

    nsurl *ubiq = [[nsfilemanager defaultmanager]                    urlforubiquitycontaineridentifier:nil]; if (ubiq)     {     nserror *error = nil;     nsfilemanager *filemanager = [nsfilemanager defaultmanager];     nsurl *cloudcontainerurl = [filemanager urlforubiquitycontaineridentifier:nil]:     nsurl*dirurl=[cloudcontainerurl urlbyappendingpathcomponent:@"documents" isdirectory:yes];     [filemanager createdirectoryaturl:dirurl withintermediatedirectories:no  attributes:nil error:&error];      nsurl *icloudurl = [dirurl urlbyappendingpathcomponent:@"passwords file.txt"];      nsarray *paths = nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes);     nsstring *documentspath = [paths objectatindex:0];      // destination path     nsstring *fileindocumentspath = [documentspath  stringbyappendingpathcomponent:@"passwords file.txt"];      nsurl* sandboxdocumenturl = [nsurl fileurlwithpath:fileindocumentspath];    [[ nsfilemanager defaultmanager ] copyitematurl:icloudurl tourl:sandboxdocumenturl error:&error ]; 

you can't copy file icloud local directory, because file might not exist on local device yet. app's icloud files downloaded on demand, , haven't done create demand. result, there's no source file copy. if know file in cloud, can't access until exists locally.

if checking error parameter passed copyitematurl:tourl:error: might know this.

to download file use -[nsfilemanager startdownloadingubiquitousitematurl:error:]. begins process. can find out when download finishes using 1 of:

• nsmetadataquery, post update when download finishes, or
• nsfilemanager, won't notify have nsurlubiquitousitemisdownloadedkey flag can check.