Question

I have a case where I need to open a new UIViewController on IBAction. This new UIViewController is supposed to be transparent. When I do a normal modal transition it hides the old UIViewController. Any suggestions on this?

Answer 1

For your purposes you will want to tell your modal View Controllers view property to change alpha. (best done in the view controllers viewDidLoad)

It’s as simple as:

- (void) viewDidLoad
{
[self.view setAlpha:0.5];
}

Now, the other approach would be to just use a new UIView added as a subview of your main view controller. The following will show your how to animate it in.

UIView *myNewView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];
[myNewView setAlpha:0.0];
[self.view addSubview:myNewView];

[UIView animateWithDuration:1.5 animations:^{
    [myNewView setAlpha:0.5];
}];

EDIT: To change the alpha of the background view and preserve the alpha of its subviews, try setting it up like this.

[myNewView setBackgroundColor:[[UIColor blueColor] colorWithAlphaComponent:0.2]];

[myNewViewsSubView setBackgroundColor:[[UIColor redColor] colorWithAlphaComponent:1.0]];