OSX application loses permissions to read a directory after app re-start

Question

My OSX application is intended to monitor a folder on the computer which the user has selected. Very simply, I have a function which scans the directory:

- (NSError*)scan:(NSString*)dir {
  NSError *err = nil;
  NSArray *filenames = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:dir error:&err];
  for(NSString* fn in filenames) {
    NSString *fp = [dir stringByAppendingPathComponent:fn];
    BOOL isDir;
    BOOL exists = [[NSFileManager defaultManager] fileExistsAtPath:fp isDirectory:&isDir];
    if(exists && isDir) {
      [self scan:fp];
    }
    else {
      [self handleFile:fp];
    }
  }
  NSLog(@"Scanning %@: %@",dir,err);
  return err;
}

When I first start the application, I present a UI to select the folder and then immediately scan it. The operation works great (no errors).

When I restart the application, I attempt to scan the directory again, but this time the NSLog spits out an error:

Scanning /Users/zane/Dropbox/Gifs: Error Domain=NSCocoaErrorDomain Code=257 "The file “Gifs” couldn’t be opened because you don’t have permission to view it." UserInfo=0x608000476d40 {NSFilePath=/Users/zane/Dropbox/Gifs, NSUserStringVariant=(
    Folder
), NSUnderlyingError=0x60800005d3d0 "The operation couldn’t be completed. (OSStatus error -5000.)"} 

Note that the path has not changed.

I suspect that the problem has to do with .entitlements . Here's what I've got:

Answer 1

If you are going to use the same file or folder the user already selected, then you need to save the path as a security-scoped bookmark when the user selects that path. Read its bookmark data when the user restarts the application in order to use the saved path. There's a description of security-scoped bookmark at the middle of this page . Use the URLByResolvingBookmarkData method of NSURL to return a security-scoped bookmark. Use the bookmarkDataWithOptions method or equivalent of NSURL to resume the security-scoped bookmark.