Question

I have added a subview over my UITableView using:

TransparentViewController *tvc =
        [[TransparentViewController alloc] 
                initWithNibName:@"TransparentViewController" bundle:nil];
[self.view addSubview:tvc.view];

My Nib has a UIImageView in it that has some text and a transparent background.

When I load the detailView for the table for the first time I show the subview that gives a brief explanation of the information that you can see below the text. Works really well.

What i would like to do is alter the alpha of the underlying table so that it is dimmer but not affect the alpha of the overlay subview. If i use:

[self.view setAlpha:(CGFloat)];

It dims the overlay as well. I seem to be having a mental block.

Answer 1

Changing the alpha affects the subviews as well. Your tvc.view is a subview of self.view, so it is naturally going to be affected.

Why don’t you try this: put another view in tvc.view and send this view to this view to the back.

(UIView*) back = [[UIView alloc] initWithFrame:CGFrameMake(...)];
back.backgroundColor = [UIColor grayColor]; // choose a color that you like;
back.alpha = 0.5; // whatever works for you
[tvc.view addSubview:back];
[tvc.view sendSubviewToBack:back];

Set the size and alpha of this new view to something you like. The table view will show through it to a limited extent, which may accomplish what you are trying to do.

Since this is part of our tvc view, it will appear when you show that view and go away when you hide that view.