Check if a subview is in a view

Question

I'm making an app where I add a subview to a view using addSubview: on an IBAction. In the same way, when the button with that IBAction is touched again should call removeFromSuperview on that subview added on that IBAction:

PSEUDO CODE

-(IBAction)showPopup:(id)sender 
{
    System_monitorAppDelegate *delegate = (System_monitorAppDelegate *)[[UIApplication sharedApplication] delegate];
    UIView *rootView = delegate.window.rootViewController.view;

    if([self popoverView] is not on rootView) 
    { 
        [rootView addSubview:[self popoverView]];
    } 
    else 
    {
        [[self popoverView] removeFromSuperview];
    }

}

score 277 · Accepted Answer · edited Mar 09 '17 at 11:24

277

You are probably looking for UIView's -(BOOL)isDescendantOfView:(UIView *)view; taken in UIView class reference.

Return Value YES if the receiver is an immediate or distant subview of view or if view is the receiver itself; otherwise NO.

You will end up with a code like :

Objective-C

- (IBAction)showPopup:(id)sender {
    if(![self.myView isDescendantOfView:self.view]) { 
        [self.view addSubview:self.myView];
    } else {
        [self.myView removeFromSuperview];
    }
}

Swift 3

@IBAction func showPopup(sender: AnyObject) {
    if !self.myView.isDescendant(of: self.view) {
        self.view.addSubview(self.myView)
    } else {
        self.myView.removeFromSuperview()
    }
}

edited Mar 09 '17 at 11:24

palme

2,499
2
21
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answered Sep 14 '11 at 18:43

2

Doesn't works, just adds the view over it. I'll edit the code to show the real case – pmerino Sep 14 '11 at 18:47
@zad0xsis - I don't understand the real case. If you added the second view using `addSubview:` method (which is probably the case the first time), the next time, you'll reach the else part because the second view now **is** a subview of the first. Isn't it what you were trying to do ? You are maybe looking another mecanism like prensenting a view controller modally ? – Sep 14 '11 at 18:57
well, `popoverView`is a subview of rootView (rootViewController). I want to check if it's on screen (if it has rootView as superview) and if so remove it or else add it if it's not – pmerino Sep 14 '11 at 19:09
is `[self popoverView]` returning a newly created popover each time? it cannot add a view "over it" if it's the same view, adding a view that's already there is a no-op. if the `popoverView` method is creating a new one every time, then it will always not be in the view hierarchy – bshirley Sep 15 '11 at 00:59
@zad0xsis Would you clarify what you mean by "just adds the view over it"? Does that happen on the first call when the view should display, or on the second when the view should hide? – paulmelnikow Sep 15 '11 at 02:57
1

One important consideration that tripped me up here: when removing then adding subviews that you're holding onto with IBOutlet properties (or ivars) you need to make sure the properties (ivars) are _strong_, or that (pre ARC) they're retain. By default if you ctrl-drag from a view to a controller to create an outlet, it will create it as _weak_ because it assumes that the view created in the nib will own it so you dont need a strong reference. But if you then remove it programmatically, it will dealloc the control and set your reference to nil (in ARC). – Rhubarb Nov 01 '12 at 17:24
Note also that Objective-C is so lenient about calling methods on `nil` that you won't see any exception when your view references are dealloced only weird behaviour like missing views – Rhubarb Nov 01 '12 at 17:24
It worked for me. I am checking whether particular element exist in tableview cell or not – Chirag Purohit Nov 16 '17 at 17:31

score 19 · Answer 2 · answered Sep 14 '11 at 18:41

19

Try this:

-(IBAction)showPopup:(id)sender
{
    if (!myView.superview)
        [self.view addSubview:myView];
    else
        [myView removeFromSuperview];
}

answered Sep 14 '11 at 18:41

Mark Granoff

16,878
2
59
61

awesome! sometimes it needs myView.view.superview, but it worked like magic for me. Thanks @MarkGranoff – Lior Frenkel Sep 21 '11 at 05:41

score 11 · Answer 3 · answered Sep 14 '11 at 18:43

11

    UIView *subview = ...;
    if([self.view.subviews containsObject:subview]) {
        ...
    }

answered Sep 14 '11 at 18:43

Michael Frederick

16,664
3
43
58

Doesn't works, just adds the view over it. I'll edit the code to show the real case – zad0xsis 1 min ago edit – pmerino Sep 14 '11 at 18:50
12

@pmerino Congrats for being that lazy that you also copied "zad0xsis 1 min ago edit" :-) – Thomas Kekeisen Jan 26 '13 at 15:09
I think this is more expensive than the other solutions to be honest because it has to iterate through all subviews – SimplyKiwi May 05 '16 at 14:48

score 4 · Answer 4 · edited Aug 03 '15 at 17:31

4

The Swift equivalent will look something like this:

if(!myView.isDescendantOfView(self.view)) {
    self.view.addSubview(myView)
} else {
    myView.removeFromSuperview()
}

edited Aug 03 '15 at 17:31

Alex Zavatone

4,106
36
54

answered Jun 16 '15 at 10:02

JaySH

546
6
15

score 2 · Answer 5 · answered Sep 14 '11 at 18:41

2

Check the superview of the subview...

-(IBAction)showPopup:(id)sender {
    if([[self myView] superview] == self.view) { 
        [[self myView] removeFromSuperview];           
    } else {
        [self.view addSubview:[self myView]];         
    }
}

answered Sep 14 '11 at 18:41

Jason Harwig

43,743
5
43
44

score 1 · Answer 6 · answered Sep 14 '11 at 19:18

1

Your if condition should go like

if (!([rootView subviews] containsObject:[self popoverView])) { 
    [rootView addSubview:[self popoverView]];
} else {
    [[self popoverView] removeFromSuperview];

}

answered Sep 14 '11 at 19:18

Saran

6,274
3
39
48

This is a slight modification of Michael Frederick's answer. Does it give different results from Vincent's code which uses `isDescendantOfView:`? – paulmelnikow Sep 15 '11 at 02:59
It absolutely yields a different result. This only checks if it is a child view, not a grandchild or great grandchild, etc. – Sami Samhuri Jul 30 '14 at 01:41

score 0 · Answer 7 · answered Jul 27 '20 at 06:00

0

Here we used two different views. Parent view is the view in which we are searching for descendant view and check wether added to parent view or not.

if parentView.subviews.contains(descendantView) {
   // descendant view added to the parent view.
}else{
  // descendant view not added to the parent view.
}

answered Jul 27 '20 at 06:00

shubham

611
7
16

I think the problem here is that if a view is a subview of a subview, it won't be found. – Ali Pacman Dec 11 '21 at 17:01

Check if a subview is in a view

7 Answers7

Objective-C

Swift 3

Linked