How to disable touch input to all views except the top-most view?

Question

I have a view with multiple subviews. When a user taps a subview, the subview expands in size to cover most of the screen, but some of the other subviews are still visible underneath.

I want my app to ignore touches on the other subviews when one of the subviews is "expanded" like this. Is there a simple way to achieve this? I can write code to handle this, but I was hoping there's a simpler built-in way.

Answer 1

Hope this help...

[[yourSuperView subviews]
   makeObjectsPerformSelector:@selector(setUserInteractionEnabled:)
   withObject:[NSNumber numberWithBool:FALSE]];

which will disable userInteraction of a view's immediate subviews..Then give userInteraction to the only view you wanted

yourTouchableView.setUserInteraction = TRUE;

EDIT:

It seems in iOS disabling userInteraction on a parent view doesn't disable userInteraction on its childs.. So the code above (I mean the one with makeObjectsPerformSelector:)will only work to disable userInteraction of a parent's immediate subviews..

See user madewulf's answer which recursively get all subviews and disable user interaction of all of them. Or if you need to disable userInteraction of this view in many places in the project, You can categorize UIView to add that feature.. Something like this will do..

@interface UIView (UserInteractionFeatures)
-(void)setRecursiveUserInteraction:(BOOL)value;
@end

@implementation UIView(UserInteractionFeatures)
-(void)setRecursiveUserInteraction:(BOOL)value{
    self.userInteractionEnabled =   value;
    for (UIView *view in [self subviews]) {
        [view setRecursiveUserInteraction:value];
    }
}
@end

Now you can call

[yourSuperView setRecursiveUserInteraction:NO];

Also user @lxt's suggestion of adding an invisible view on top of all view's is one other way of doing it..

Answer 2

There are a couple of ways of doing this. You could iterate through all your other subviews and set userInteractionEnabled = NO, but this is less than ideal if you have lots of other views (you would, after all, have to subsequently renable them all).

The way I do this is to create an invisible UIView that's the size of the entire screen that 'blocks' all the touches from going to the other views. Sometimes this is literally invisible, other times I may set it to black with an alpha value of 0.3 or so.

When you expand your main subview to fill the screen you can add this 'blocking' UIView behind it (using insertSubview: belowSubview:). When you minimize your expanded subview you can remove the invisible UIView from your hierarchy.

So not quite built-in, but I think the simplest approach. Not sure if that was what you were thinking of already, hopefully it was of some help.

Answer 3

Beware of the code given as solution here by Krishnabhadra:

[[yourSuperView subviews]makeObjectsPerformSelector:@selector(setUserInteractionEnabled:) withObject:[NSNumber numberWithBool:FALSE]];

This will not work in all cases because [yourSuperView subviews] only gives the direct subviews of the superview. To make it work, you will have to iterate recursively on all subviews:

-(void) disableRecursivelyAllSubviews:(UIView *) theView
{
    theView.userInteractionEnabled = NO;
    for(UIView* subview in [theView subviews])
    {
        [self disableRecursivelyAllSubviews:subview];
    }
}

-(void) disableAllSubviewsOf:(UIView *) theView
{
    for(UIView* subview in [theView subviews])
    {
        [self disableRecursivelyAllSubviews:subview];
    }
} 

Now a call to disableAllSubviewsOf will do what you wanted to do.

If you have a deep stack of views, the solution by lxt is probably better.