Slider is hidden by UITableViewCell, when cell height is to small about asvaluetrackingslider

[alskipp]

OK, I've identified the problem.

The view hierarchy of UITableView is working against us. The bottom UITableViewCell is rendered first and the top cell is rendered last. This means that content protruding outside a UITableViewCell is obscured by the UITableViewCell above.

Does your table view use static cells? If so, there might be a quick fix for you. In the header of your UITableViewController set an IBOutlet to the cell with the slider.

@property (weak, nonatomic) IBOutlet UITableViewCell *sliderCell;

Then bring the cell to the front when it displays.

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (cell == self.sliderCell) {
        [self.sliderCell.superview bringSubviewToFront:self.sliderCell];
    }
}

Let me know if this helps. In the meantime I'll look into a more general solution to the issue.

[alskipp]

Thanks for raising the issue. I'll have a look into it.

I wonder if setting the ‘ clipsToBounds’ property of the UITableViewCell to ‘NO’ would fix the issue? I've not tried this yet, but I will do when I get a spare moment.

[Ma-He]

Thanks a lot for your quick reply! Your second solution works like a charm. You made my day ;-)

[alskipp]

I'm glad it helped!

I'll keep the issue open for now because you'll find that if you have 2 sliders in a table view, one above the other, then that solution isn't so effective (the lower slider can still be obscured by the one above).

What I'll need to implement is either a notification or a delegate call back. Something like this:

@protocol ASValueTrackingSliderDelegate <NSObject>
- (void)sliderWillDisplayPopUpView:(ASValueTrackingSlider *)slider;
@end

If you're embedding the slider in a tableView, you'd register as a delegate of the slider and implement the delegate method. You'd then be given the chance to bring the slider’s tableViewCell to the front of the view hierarchy before the popUpView appears.

[alskipp]

The latest commit 6dfeec9 should have solved the issue with TableViews. I've also added a TableView to the example project which demonstrates how it should be used.

To do:

• Update README with UITableView instructions

[pventura1976]

This is not working right now in iPad Air (7.0.6) physical device; but YES in iPhone 4S (7.1.2) physical device and all simulators.

You can check it out with the sample app.

[alskipp]

Hi thanks for your input,
I've just tested this on an iPad 3 and there weren't any issues. Do you have any more details about the issue? Is there a specific series of events that causes the unexpected behaviour?

[pventura1976]

It happens with my app but also with the sample app. Here is an screenshot. Just run the app, go to tableview sample and move the slider.

[alskipp]

Hmm, that is strange. Which version of ASValueTrackingSlider are you using?

It's going to be difficult for me to track down the problem because when testing on an iPad 3 the TableView Example works as expected for me. Could you add a breakpoint, or an NSLog to confirm that the delegate method is being called in SliderCell.m in the TableView Example?

This is the method which should ensure the table cell is brought to the front of the view hierarchy:

- (void)sliderWillDisplayPopUpView:(ASValueTrackingSlider *)slider;
{
    [self.superview bringSubviewToFront:self];
}

[pventura1976]

Here is the version I'm using: 0.9.3

The code that is running:

- (void)sliderWillDisplayPopUpView:(ASValueTrackingSlider *)slider;
{
    NSLog(@"Before bringSubviewToFront");

    [self.superview bringSubviewToFront:self];

    NSLog(@"After bringSubviewToFront");
}

The console results:

2014-07-11 17:59:08.147 ValueTrackingSlider[2004:60b] Before bringSubviewToFront
2014-07-11 17:59:08.148 ValueTrackingSlider[2004:60b] After bringSubviewToFront
2014-07-11 17:59:10.412 ValueTrackingSlider[2004:60b] Before bringSubviewToFront
2014-07-11 17:59:10.413 ValueTrackingSlider[2004:60b] After bringSubviewToFront
2014-07-11 17:59:11.996 ValueTrackingSlider[2004:60b] Before bringSubviewToFront
2014-07-11 17:59:11.998 ValueTrackingSlider[2004:60b] After bringSubviewToFront

What else can I do to help you find out what is happening? I'm your hands.

[alskipp]

Well the delegate method is getting called - which is good. Perhaps there's something unexpected in the view hierarchy? Could you try using the implementation below and see what results you get?

- (void)sliderWillDisplayPopUpView:(ASValueTrackingSlider *)slider;
{
    [self.superview bringSubviewToFront:self];

    UIView *view = self;
    int i = 1;
    while (view) {
        NSLog(@"%d: %@", i, view.class);
        view = view.superview;
        i++;
    }
}

Here's what I get:

2014-07-11 17:16:05.261 ValueTrackingSlider[4006:60b] Before bringSubviewToFront
2014-07-11 17:16:05.264 ValueTrackingSlider[4006:60b] 1: SliderCell
2014-07-11 17:16:05.266 ValueTrackingSlider[4006:60b] 2: UITableViewWrapperView
2014-07-11 17:16:05.268 ValueTrackingSlider[4006:60b] 3: UITableView
2014-07-11 17:16:05.269 ValueTrackingSlider[4006:60b] 4: UIViewControllerWrapperView
2014-07-11 17:16:05.271 ValueTrackingSlider[4006:60b] 5: UINavigationTransitionView
2014-07-11 17:16:05.273 ValueTrackingSlider[4006:60b] 6: UILayoutContainerView
2014-07-11 17:16:05.274 ValueTrackingSlider[4006:60b] 7: UIWindow

[pventura1976]

Ok. Here is what I get:

2014-07-12 06:58:37.883 ValueTrackingSlider[2136:60b] 1: SliderCell
2014-07-12 06:58:37.884 ValueTrackingSlider[2136:60b] 2: UITableViewWrapperView
2014-07-12 06:58:37.885 ValueTrackingSlider[2136:60b] 3: UITableView
2014-07-12 06:58:37.886 ValueTrackingSlider[2136:60b] 4: UIViewControllerWrapperView
2014-07-12 06:58:37.886 ValueTrackingSlider[2136:60b] 5: UINavigationTransitionView
2014-07-12 06:58:37.888 ValueTrackingSlider[2136:60b] 6: UILayoutContainerView
2014-07-12 06:58:37.888 ValueTrackingSlider[2136:60b] 7: UIWindow

It is the same.
Could it be because my iPad is jailbroken and not updated to the latest iOS release?

[appicus]

I have had exactly the same issue on iPad Air iOS 7.0.6 but now after upgrading it to 7.1.2 ASValueTrackingSlider is working fine again. The question is why does it not work on 7.0.6

[pventura1976]

At least we have a workaround!

[alskipp]

Thanks @appicus,
Your input is most welcome and has saved me quite a bit of bewilderment! I have a vague recollection that in 7.0.6 the implementation of UITableViewCell changed temporarily - I think there might be a hidden container view that receives the message to super and that's why the cell isn't brought to the front of the view hierarchy.

@pventura1976 could you just try the code below to see what results you get?

- (void)sliderWillDisplayPopUpView:(ASValueTrackingSlider *)slider;
{
    NSLog(@"Before index:%d", (int)[self.superview.subviews indexOfObject:self]);
    [self.superview bringSubviewToFront:self];
    NSLog(@"After index:%d", (int)[self.superview.subviews indexOfObject:self]);
}

Here are the results I get:

2014-07-12 09:22:23.549 ValueTrackingSlider[14552:1381883] Before index:2
2014-07-12 09:22:23.551 ValueTrackingSlider[14552:1381883] After index:5
2014-07-12 09:22:26.605 ValueTrackingSlider[14552:1381883] Before index:1
2014-07-12 09:22:26.605 ValueTrackingSlider[14552:1381883] After index:5

There are 6 cells in the example tableview so the After index should always be 5. If my conjecture is correct you should get a different result.

My guess is that this very dodgy code might work in 7.0.6. Whatever you do, don't actually use this code, as it will fail in all other iOS versions.

    [self.superview.superview bringSubviewToFront:self];

Actually, that might need to be even dodgier:

    [self.superview.superview bringSubviewToFront:self.superview];

[pventura1976]

Here is the result, the same as your at "after index":

2014-07-12 13:58:53.564 ValueTrackingSlider[443:60b] Before index:3
2014-07-12 13:58:53.565 ValueTrackingSlider[443:60b] After index:5
2014-07-12 13:58:57.963 ValueTrackingSlider[443:60b] Before index:2
2014-07-12 13:58:57.964 ValueTrackingSlider[443:60b] After index:5
2014-07-12 13:59:00.580 ValueTrackingSlider[443:60b] Before index:3
2014-07-12 13:59:00.581 ValueTrackingSlider[443:60b] After index:5
2014-07-12 13:59:03.680 ValueTrackingSlider[443:60b] Before index:2
2014-07-12 13:59:03.681 ValueTrackingSlider[443:60b] After index:5
2014-07-12 13:59:07.996 ValueTrackingSlider[443:60b] Before index:1
2014-07-12 13:59:07.997 ValueTrackingSlider[443:60b] After index:5

None of these tricks worked:

[self.superview.superview bringSubviewToFront:self];
[self.superview.superview bringSubviewToFront:self.superview];

[alskipp]

Well now I am at a loss. If the table view cell is being brought to the front of the view hierarchy then the popup view shouldn't be obscured. Other than updating from 7.0.6, I'm not sure what to suggest. I don't have a device running 7.0.6, so I'm unable to investigate the cause. If you dig around in the view hierarchy you may discover the problem, but it's probably simpler to just update the iOS version on your device.

[pventura1976]

It is not worth it. In my personal case, for now, I'll increase the height of the cell a bit.

[vitaliypriydun]

It can happen if you are calling [tableview reloadData] after changing slider value like I did.
So I haven`t found a way to dodge this and moved it from valueChanged to didFinishEditing