これを試してください:
actionSheet = [[UIActionSheet alloc] initWithTitle:@"Select Font Name?"
delegate:self
cancelButtonTitle:nil
destructiveButtonTitle:nil
otherButtonTitles:@"OK", nil];
UIToolbar *pickerDateToolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
pickerDateToolbar.barStyle = UIBarStyleBlackOpaque;
[pickerDateToolbar sizeToFit];
NSMutableArray *barItems = [[NSMutableArray alloc] init];
UIBarButtonItem *flexSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:self action:nil];
[barItems addObject:flexSpace];
UIBarButtonItem *doneBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(dismissActionSheet)];
[barItems addObject:doneBtn];
[pickerDateToolbar setItems:barItems animated:YES];
[actionSheet addSubview:pickerDateToolbar];
[actionSheet showInView:self.view];
[actionSheet setBounds:CGRectMake(0,0,320,390)];//set it with your way
役立つかもしれません。幸せなコーディング...