startAccessingSecurityScopedResource never returns success

I'm developing a sandboxed Mac App Store app which asks the user where to save files it downloads from elsewhere. I have this code to get the folder from the user (stripping out some error checking):

NSOpenPanel* openPanel = [NSOpenPanel openPanel];
[openPanel setAllowsMultipleSelection:NO];
[openPanel setCanChooseDirectories:YES];
[openPanel setResolvesAliases:YES];
NSInteger result = [openPanel runModal];
NSArray* urls = [openPanel URLs];
NSURL* folderURL = [urls objectAtIndex:0];
NSError* error;
NSData* bookmakeData = [folderURL bookmarkDataWithOptions:NSURLBookmarkCreationWithSecurityScope
                           includingResourceValuesForKeys:nil
                                            relativeToURL:nil
                                                    error:&error];
_saveFolderBookmark = bookmakeData;

and when it comes time to move a file into this folder, I have this code:

BOOL isStale;
NSError* error;
NSURL* saveFolder = [NSURL URLByResolvingBookmarkData:_saveFolderBookmark
                                              options:NSURLBookmarkCreationWithSecurityScope
                                        relativeToURL:nil
                                  bookmarkDataIsStale:&isStale
                                                error:&error];
BOOL success = [saveFolder startAccessingSecurityScopedResource];

// Move the file somewhere else
NSWorkspace* workspace = [NSWorkspace sharedWorkspace];
NSInteger operationTag;
BOOL copied = [workspace performFileOperation:NSWorkspaceMoveOperation
                                       source:[[self getDocumentsFolder] path]
                                  destination:[saveFolder path]
                                        files:[NSArray arrayWithObject:filename]
                                          tag:&operationTag];
[saveFolder stopAccessingSecurityScopedResource];

Which is a lot of code to list to say that startAccessingSecurityScopedResource never returns success for me, either immediately after getting the ULR from NSOpenPanel or in a later run, with the bookmark data being saved in NSUserDefaults.

In the entitlements file, amongst other items, I have:

<key>com.apple.security.files.bookmarks.app-scope</key>
<true/>

Is there anything wrong with this code?

This one is very easy. You're resolving with NSURLBookmarkCreationWithSecurityScope instead of NSURLBookmarkResolutionWithSecurityScope. Just change that line and it should work.

(It may not work during the same session where you create the bookmark, when you already have access to the URL, because you're not supposed to call it in that case. But on later runs it should, of course, because that's the whole point.)