performSelector:withObject:afterDelay: not making call

in a method, i want to call a method after n seconds:

    self.toolBarState = [NSNumber numberWithInt:1];
    [self changeButtonNames];
    [self drawMap];
    [self performSelector:@selector(showActionSheet) withObject:nil afterDelay:2];

i want to show the action sheet 2 seconds after drawMap is complete. when i use this performSelector, it never makes the call.

if i just put [self showActionSheet];, it works just fine. is there reason why the performSelector is not making the call?

EDIT: in another part of my code, i make the same call and it works:

HUD = [[MBProgressHUD alloc] initWithView:self.view];
[self.view addSubview:HUD];
HUD.delegate = (id) self;
[HUD showWhileExecuting:@selector(drawMap) onTarget:self withObject:nil animated:YES];

[self performSelector:@selector(showActionSheet) withObject:nil afterDelay:6];

here, the showActionSheet gets called 6 seconds after drawMap has completed. i'm guessing there is something going on with the threads that i don't understand yet...

EDIT2:

-(void)showActionSheet
{
    InspectAppDelegate *dataCenter = (InspectAppDelegate *) [[UIApplication sharedApplication] delegate];

    if (dataCenter.fieldIDToPass == nil)
    {
        UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"Selected Boundary Options" delegate:(id) self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:@"Analyze a Field",@"Retrieve Saved Analysi", @"Geotag Photos", @"Refresh the map",nil];
        actionSheet.tag = 0;
        [actionSheet showInView:self.view];
    }
    else
    {
        UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"Selected Boundary Options" delegate:(id) self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:@"Analyze a Field",@"Retrieve Saved Analysi", @"Geotag Photos", @"Attribute the Field", @"Refresh the map",nil];
        actionShee