Click events in UINavigationBar overridden by the gesture recognizer

The question in the first place was:

When you have a tableView how to implement that the user can tap the NavigationBar to scroll all the way to the top.

Solution:

- (void)viewDidLoad {
    UITapGestureRecognizer* tapRecon = [[UITapGestureRecognizer alloc]
              initWithTarget:self action:@sele开发者_如何学Goctor(navigationBarDoubleTap:)];
    tapRecon.numberOfTapsRequired = 2;
    [navController.navigationBar addGestureRecognizer:tapRecon];
    [tapRecon release];
}

- (void)navigationBarDoubleTap:(UIGestureRecognizer*)recognizer {
    [tableView setContentOffset:CGPointMake(0,0) animated:YES];
}

Which works like a charm!

But Drarok pointed out an issue:

This approach is only viable if you don't have a back button, or rightBarButtonItem. Their click events are overridden by the gesture recognizer

My question:

How can I have the nice feature that my NavigationBar is clickable but still be able to use the back buttons in my app?

So either find a different solution that doesn't override the back button or find a solution to get the back button back to working again :)

---

Rather than using location view, I solved this by checking the class of the UITouch.

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
    return (![[[touch view] class] isSubclassOfClass:[UIControl class]]);
}

Note that the nav buttons are of type UINavigationButton which is not exposed, hence the subclass checking.

This method goes in the class you designate as the delegate of the gesture recognizer. If you're just getting started with gesture recognizers, note that the delegate is set separately from the target.

---

UIGestureRecognizerDelegate has a method called "gestureRecognizer:shouldReceiveTouch". If you are able to point out if the touch's view is the button, just make it return "NO", otherwise return "YES" and you're good to go.

---

UIGestureRecognizer also has an attribute @property(nonatomic) BOOL cancelsTouchesInView. From the documentation: A Boolean value affecting whether touches are delivered to a view when a gesture is recognized.

So if you simply do

tapRecon.cancelsTouchesInView = NO;

this might be an even simpler solution, depending on your use case. This is how I do it in my app.

When pressing a button in the navigation bar though, its action is executed (as desired), but the UIGestureRecognizer's action is executed as well. If that doesn't bother you, then that would be the simplest solution I could think of.

---

iOS7 version:

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
    CGPoint point = [touch locationInView:touch.view];
    UINavigationBar *naviagationBar = (UINavigationBar *)touch.view;
    NSString *navigationItemViewClass = [NSString stringWithFormat:@"UINavigationItem%@%@",@"Button",@"View"];
    for (id subview in naviagationBar.subviews) {

        if (([subview isKindOfClass:[UIControl class]] ||
             [subview isKindOfClass:NSClassFromString(navigationItemViewClass)]) &&
             [subview pointInside:point withEvent:nil]) {

            return NO;
        }
    }
    return YES;
}

EDIT:

Someting on the corner of back button gesture is still overwritten, so you this code insted of pointInside:withEvent:

CGRectContainsPoint((CGRect){ .origin = subview.frame.origin, .size = CGSizeMake(subview.frame.size.width + 16, subview.frame.size.height)}, point)

---

Xamarin.iOS does not expose C# wrappers for Objective-C classes in the private API, so the neat subclass checking suggested by @ben-flynn above won't work here.

A somewhat hackish workaround is to check the Description field of the views:

navigationTitleTap = new UITapGestureRecognizer (tap => DidTapNavigationTitle());

navigationTitleTap.ShouldReceiveTouch = (recognizer, touch) => 
    touch.View.Subviews.Any(sv => 
        // Is this the NavigationBar's title or prompt?
        (sv.Description.StartsWith("<UINavigationItemView") || sv.Description.StartsWith("<UINavBarPrompt")) &&
        // Was the nested label actually tapped?
        sv.Subviews.OfType<UILabel>().Any(label =>
            label.Frame.Contains(touch.LocationInView(sv))));

NavigationController.NavigationBar.AddGestureRecognizer (navigationTitleTap);

The Linq collection filter .OfType<T> is convenient though when fishing for certain types in the view hierarchy.

---

This worked for me, It is based on Stavash answer. I use the view property of the gesture recognizer to return YES/NO in the delegate method.

It is an old app so obviously this is not ARC, does not use new layout stuff nor NSAttributed strings. I leave that to you :p

- (void)viewDidLoad
{
    ...
    CGRect r = self.navigationController.navigationBar.bounds;
    UILabel *titleView = [[UILabel alloc] initWithFrame:r];
    titleView.autoresizingMask = 
      UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
    titleView.textAlignment = NSTextAlignmentCenter;
    titleView.font = [UIFont systemFontOfSize:[UIFont systemFontSize]];
    titleView.text = self.title;
    titleView.userInteractionEnabled = YES;
    UITapGestureRecognizer *tgr =
      [[UITapGestureRecognizer alloc] initWithTarget:self
                                              action:@selector(titleViewWasTapped:)];
    tgr.numberOfTapsRequired = 1;
    tgr.numberOfTouchesRequired = 1;
    tgr.delegate = self;
    [titleView addGestureRecognizer:tgr];
    [tgr release];
    self.navigationItem.titleView = titleView;
    [titleView release];
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
       shouldReceiveTouch:(UITouch *)touch
{
    // This method is needed because the navigation bar with back
    // buttons will swallow touch events
    return (gestureRecognizer.view == self.navigationItem.titleView);
}

Then you use the gesture recogniser as usual

- (void)titleViewWasTapped:(UIGestureRecognizer *)gestureRecognizer
{
    if (gestureRecognizer.state != UIGestureRecognizerStateRecognized) {
        return;
    }
    ...
}