How to prevent UINavigationBar from blocking touch

问题:

I have a UIView that is partially stuck underneath a UINavigationBar on a UIViewController that's in full screen mode. The UINavigationBar blocks the touches of this view for the portion that it's covering it. I'd like to be able to unblock these touches for said view and have them go through. I've subclassed UINavigationBar with the following:

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
    UIView *view = [super hitTest:point withEvent:event];

    if (view.tag == 399)
    {
        return view;
    }
    else
    {
        return nil;
    }
}

...where I've tagged the view in question with the number 399. Is it possible to pass through the touches for this view without having a pointer to it (i.e. like how I've tagged it above)? Am a bit confused on how to make this work with the hittest method (or if it's even possible).

回答1:

Subclass UINavigationBar and override- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event such that it returns NO for the rect where the view you want to receive touches is and YES otherwise.

For example:

UINavigationBar subclass .h:

@property (nonatomic, strong) NSMutableArray *viewsToIgnoreTouchesFor; 

UINavigationBar subclass .m:

- (NSMutableArray *)viewsToIgnoreTouchesFor
{
    if (!_viewsToIgnoreTouchesFor) {
        _viewsToIgnoreTouchesFor = [@[] mutableCopy];
    }
    return _viewsToIgnoreTouchesFor;
}

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
    BOOL pointInSide = [super pointInside:point withEvent:event];
    for (UIView *view in self.viewsToIgnoreTouchesFor) {

        CGPoint convertedPoint = [view convertPoint:point fromView:self];
        if ([view pointInside:convertedPoint withEvent:event]) {
            pointInSide = NO;
            break;
        }
    }

    return pointInSide;
}

In your fullscreen viewController where you have the view behind the navBar add these lines to viewDidLoad

UINavigationBarSubclass *navBar = 
(UINavigationBarSubclass*)self.navigationController.navigationBar;
[navBar.viewsToIgnoreTouchesFor addObject:self.buttonBehindBar];

Please note: This will not send touches to the navigationBar, meaning if you add a view which is behind buttons on the navBar the buttons on the navBar will not receive touches.

Swift:

var viewsToIgnore = [UIView]()

override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {

    let ignore = viewsToIgnore.first {
        let converted = $0.convert(point, from: self)
        return $0.point(inside: converted, with: event)
    }
    return ignore == nil && super.point(inside: point, with: event)
}

---

See the documentation for more info on pointInside:withEvent:

Also if pointInside:withEvent: does not work how you want, it might be worth trying the code above in hitTest:withEvent: instead.

回答2:

Here's a version which doesn't require setting the specific views you'd like to enable underneath. Instead, it lets any touch pass through except if that touch occurs within a UIControl or a view with a UIGestureRecognizer.

import UIKit

/// Passes through all touch events to views behind it, except when the
/// touch occurs in a contained UIControl or view with a gesture
/// recognizer attached
final class PassThroughNavigationBar: UINavigationBar {

    override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
        guard nestedInteractiveViews(in: self, contain: point) else { return false }
        return super.point(inside: point, with: event)
    }

    private func nestedInteractiveViews(in view: UIView, contain point: CGPoint) -> Bool {

        if view.isPotentiallyInteractive, view.bounds.contains(convert(point, to: view)) {
            return true
        }

        for subview in view.subviews {
            if nestedInteractiveViews(in: subview, contain: point) {
                return true
            }
        }

        return false
    }
}

fileprivate extension UIView {
    var isPotentiallyInteractive: Bool {
        guard isUserInteractionEnabled else { return false }
        return (isControl || doesContainGestureRecognizer)
    }

    var isControl: Bool {
        return self is UIControl
    }

    var doesContainGestureRecognizer: Bool {
        return !(gestureRecognizers?.isEmpty ?? true)
    }
}