Save Thread not working NSSavePanel when Sandboxed OSX - objective-c

Question

The following function is called after the savepanel save, the application is basically to splice an image into multiple pictures - this works however when sandboxed it doesn't, I believe it's the save thread which isn't working - does anyone know why this isn't working when sandboxed
- (void)saveThread{
NSLog(#"Save thread started");
#autoreleasepool {
NSImage *image = [[NSImage alloc] initWithContentsOfFile:tileCutterView.filename];
[rowBar setIndeterminate:NO];
[columnBar setIndeterminate:NO];
[rowBar setMaxValue:(double)[image rowsWithTileHeight:[heightTextField floatValue]]];
[rowBar setMinValue:0.];
[rowBar setDoubleValue:0.];
[columnBar setMinValue:0.];
[columnBar setMaxValue:(double)[image columnsWithTileWidth:[widthTextField floatValue]]];
[columnBar setDoubleValue:0.];
progressCol = 0;
progressRow = 0;
tileRowCount = [image rowsWithTileHeight:tileHeight];
tileColCount = [image columnsWithTileWidth:tileWidth];
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
TileCutterOutputPrefs outputFormat = (TileCutterOutputPrefs)[defaults integerForKey:#"OutputFormat"];
for (int row = 0; row < tileRowCount; row++)
{
// Each row operation gets its own ImageRep to avoid contention
NSBitmapImageRep *imageRep = [[NSBitmapImageRep alloc] initWithCGImage:[image CGImageForProposedRect:NULL context:NULL hints:nil]];
TileOperation *op = [[TileOperation alloc] init];
op.row = row;
op.tileWidth = tileWidth;
op.tileHeight = tileHeight;
op.imageRep = imageRep;
op.baseFilename = baseFilename;
op.delegate = self;
op.outputFormat = outputFormat;
[queue addOperation:op];
}
}
}
UPDATE: I've added the other functions relating to this code:
- (IBAction)saveButtonPressed:(id)sender{
NSSavePanel *sp = [NSSavePanel savePanel];
[sp setRequiredFileType:#"jpg"];
[sp beginSheetForDirectory:[NSString stringWithFormat:#"%#/Pictures", NSHomeDirectory()]
file:#"output.jpg"
modalForWindow:window
modalDelegate:self
didEndSelector:#selector(didEndSaveSheet:returnCode:conextInfo:)
contextInfo:nil];
}
-(void)didEndSaveSheet:(NSSavePanel *)savePanel
returnCode:(int)returnCode conextInfo:(void *)contextInfo
{
if (returnCode == NSOKButton)
{
NSURL *fileURL = [savePanel URL];
NSString *filePath = [fileURL path];
self.baseFilename = filePath;
tileHeight = [heightTextField intValue];
tileWidth = [widthTextField intValue];
[self performSelector:#selector(delayPresentSheet) withObject:nil afterDelay:0.1];
}
}
- (void)delayPresentSheet{
[progressLabel setStringValue:#"Splicing image…"];
[rowBar setIndeterminate:YES];
[columnBar setIndeterminate:YES];
[rowBar startAnimation:self];
[columnBar startAnimation:self];
[NSApp beginSheet: progressWindow
modalForWindow: window
modalDelegate: self
didEndSelector: #selector(didEndSheet:returnCode:contextInfo:)
contextInfo: nil];
[self performSelectorInBackground:#selector(saveThread) withObject:nil];
}
UPDATE: CONSOLE ERROR:
06/05/2015 11:30:49.592 sandboxd[8455]: ([8720]) MyApp(8720) deny file-write-create /Users/Me/Documents/output_1_0.jpg
06/05/2015 11:30:49.592 sandboxd[8455]: ([8720]) MyApp(8720) deny file-write-create /Users/Me/Documents/output_1_1.jpg
06/05/2015 11:30:49.592 sandboxd[8455]: ([8720]) MyApp(8720) deny file-write-create /Users/Me/Documents/output_0_1.jpg

Answer 1

NSSavePanel can not grant you access for several files at once. You need to use a NSOpenPanel and ask the user to grant access for the whole directory. Use then the NSURL from the NSOpenPanel and add your files to this.
More explanation in the answer of your other question and in the Apple Documentation here.