Sometimes we need to show a overlay view over the main view so that user not able to click on the background view assets like button click. in order to display the overlay view use the following function--

- (void)getOverlayView{
    overlayView=[[UIView alloc]initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
    [overlayView setBackgroundColor:[UIColor colorWithRed:.35 green:.35 blue:.35 alpha:0.65]];
    YourViewController *vc=[self.storyboard instantiateViewControllerWithIdentifier:@"identifier"];
    [self addChildViewController:dsvc];
    dsvc.view.frame = CGRectMake(x, y, width , height);
    dsvc.view.center = self.view.center;
//set border colour
    [[dsvc.view layer] setBorderColor:
     [[UIColor colorWithRed: 43/255.0 green:124/255.0 blue:24/255.0 alpha:1.0] CGColor]]; 
    [[dsvc.view layer] setBorderWidth:2.75];//border width
    [self.view addSubview:overlayView];
    [self.view addSubview:dsvc.view];

    [dsvc didMoveToParentViewController:self];

//design close button 
    UIButton *closeButton = [UIButton buttonWithType:UIButtonTypeCustom];
    [closeButton setFrame:CGRectMake(dsvc.view.frame.size.width+dsvc.view.frame.origin.x-5, dsvc.view.frame.origin.y-20, 26, 26)];
    [closeButton setImage:[UIImage imageNamed:@"icon_close.png"] forState:UIControlStateNormal];
    [closeButton addTarget:self action:@selector(closeOverlay:) forControlEvents:UIControlEventTouchUpInside]; 
    [[self view] addSubview:closeButton];    
}

To close the overlay view use the following function--

-(void)closeOverlay:(id)sender {
    UIViewController *vc = [self.childViewControllers lastObject];
    [vc willMoveToParentViewController:nil];
    [vc.view removeFromSuperview];
    [vc removeFromParentViewController];
    [overlayView setHidden:YES];
    [sender setHidden:YES];
}