在变暗的UIWindow上呈现UIView

Question

I am trying to present a UIView while at the same time darkening the rest of the screen. However, I am having difficulty. This is my code:

UIWindow *window = [[UIApplication sharedApplication] keyWindow];

self.viewToDarken = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 568)];
[self.viewToDarken setBackgroundColor:[UIColor blackColor]];
[self.viewToDarken setAlpha:0.0f];
[window insertSubview:self.viewToDarken aboveSubview:self.hostView];

[self.hostView addSubview:self];


[UIView animateWithDuration:0.25f
                      delay:0.0
                    options:UIViewAnimationCurveLinear
                 animations:^(void) {
                     [self setFrame:[self destinationFrame]];
                     if (self.viewToDarken) self.viewToDarken.alpha = 0.7f;
                 }completion:^(BOOL finished) {
                     [self notifyDidShow];
                 }];

However, I can't get the view to darken to get placed below the view I am adding (self). any ideas why this doesn't work?

Thanks!

Answer 1

You are adding the viewToDarken above self.hostView then adding self to hostView so of course self will be below viewToDarken . You need to add viewToDarken below self.hostView .

What you have now is:

hostView + self(view) (below) -> viewToDarken

You need

viewToDarken (below)-> hostView + self(view)

You should have:

[window insertSubview:self.viewToDarken belowSubview:self.hostView];

Answer 2

You have 3 views here; self , hostView and viewToDarken . You are inserting the viewToDarken above hostView , and then you are adding self to the hostView. Because self is a subview of hostView , it will be below any views that hostView is below.

You probably instead want to add the viewToDarken to hostView . Or you could insert it behind the hostView like so:

[self.hostView.superview insertSubview:self.viewToDarken belowSubview:self.hostView];

Whichever way you do it, you are going to need to take into account coordinate systems. Make sure to check out -[UIView convertRect:fromView:] .

Also, instead of using absolute "magic" numbers for the frame, use window.bounds:

self.viewToDarken = [[UIView alloc] initWithFrame:window.bounds];