objective c - How do i create a file in the default documents directory in an iOS app -

i'm writing app needs store persistence information in file i'm having trouble debugging createfileatpath:contents:attributes: function of nsfilemanager, have reduced problem below piece of code.

nsfilemanager *filemgr; filemgr = [nsfilemanager defaultmanager]; nsstring * filename = @"newfile.txt";  nsarray *paths = nssearchpathfordirectoriesindomains (nsdocumentdirectory, nsuserdomainmask, yes); nsstring *documentsdirectory = [paths objectatindex:0];  nsstring *filepath = [documentsdirectory stringbyappendingpathcomponent: filename]; nslog(@"full path name: %@", filepath);  // check if file exists if ([filemgr fileexistsatpath: filepath] == yes){     nslog(@"file exists");  }else {     nslog (@"file not found, file created");     if (![filemgr createfileatpath:filepath contents:nil attributes:nil]){         nslog(@"create file returned no");     } } 

since function doesn't take nserror object i'm having trouble finding out why returning false.

from other examples have seen here write file on ios , here how programmatically create empty .m4a file of length under ios using coreaudio on device? should ok pass nil both contents , attributes parameters. i've tried specifying both parameters , receive same result.

i'm thinking may permissions issue i'm unsure if below code correct way check permissions on directory.

if ([filemgr iswritablefileatpath:documentsdirectory] == yes){     nslog (@"file readable , writable"); } 

//  following code creat directory in documentsdirectory  nsstring *docdir = nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes)[0]; nsstring *dirname = [docdir stringbyappendingpathcomponent:@"mydir"];  bool isdir nsfilemanager *fm = [nsfilemanager defaultmanager]; if(![fm fileexistsatpath:dirname isdirectory:&isdir]) {     if([fm createdirectoryatpath:dirname withintermediatedirectories:yes attributes:nil error:nil])         nslog(@"directory created");     else         nslog(@"directory creation failed"); } else     nslog(@"directory exist");