Achieve a Uniform UIBlurEffect in the Primary View of a UISplitView

Question

I'm using a stock UISplitViewController with out-of-the-box Master and Detail view controllers. In a storyboard, I've added a UIImageView to the Detail controller set to effectively fill the view with a single image.

In the Master controller, I've used the following to blur the background of that controller:

// In viewDidLoad

self.tableView.backgroundColor = [UIColor clearColor];
    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
    UIVisualEffectView *visualEffectView = [[UIVisualEffectView alloc]
                                            initWithEffect:blurEffect];
    self.tableView.backgroundView = visualEffectView;
    self.tableView.separatorEffect = [UIVibrancyEffect effectForBlurEffect:blurEffect];

When the Master controller appears above the Detail controller, note how the edges of the Master controller have a dark shadow around the inner edges.

How can these "shadows" be removed to instead render a uniform blur?

More Details

Debugging the view hierarchy in IB reveals a (private?) view called _UIPopoverSlidingChromeView. It has an inset grey frame, and it's definitely what's responsible for the non-uniform blur appearance.

Disabling the blur view altogether and just leaving self.tableview.backgroundColor = [UIColor clearColor] shows _UIPopoverSlidingChromeView's grey frame. It looks like this:

Any thoughts on how to avoid _UIPopoverSlidingChromeView when using UISplitViewController?

Answer 1

The problem is that it is a private class that you can't test against.

Fortunately _UIPopoverSlidingChromeView is the subclass of UIPopoverBackgroundView that is public (because in regular popover implementation flow client may customize the popover background chrome by providing a class which subclasses UIPopoverBackgroundView).

for (UIView *subview in self.viewController.view.superview.superview.subviews) {
    if ([subview isKindOfClass:[UIPopoverBackgroundView class]]) {
        subview.alpha = 0.0;
    }
}

This should hide the _UIPopoverSlidingChromeView.