UISegmentedControl not responding within UIView

Question

I have a UIView property named viewToFade that contains a UISegmentedControl. When I animate the UIView (so it appears on tapping and gradually fades), the UISegmentedControl doesn't respond to touches. Here's the code I'm using:

-(void)fadeView
{
self.viewToFade.alpha=1;
self.viewToFade.hidden=NO;

//When I comment the following lines out, everything is fine--the `UISegmentedControl` responds as it should.  
//But when I include them, the `UISegmentedControl` doesn't register changes/taps.

[UIView animateWithDuration:0.3
                      delay: 3.0
                    options:UIViewAnimationOptionAllowUserInteraction
                 animations:^{
                     self.viewToFade.alpha = 0.0;
                 }
                 completion:nil];
}

What am I doing wrong?

(In case it's relevant, I'll say that the UIView and the UISegmentedControl are both created in the xib file.)

EDIT: I figured out a way to deal with the problem, which was to rewrite the code as follows:

-(void)fadeView
{
self.viewToFade.alpha=1;
self.viewToFade.hidden=NO;
[self performSelector:@selector(disneyfy) withObject:nil afterDelay:(3)];
} 

-(void)disneyfy
{
    [UIView animateWithDuration:0.3
                 animations:^{
                     self.viewToFade.alpha = 0.0;
                 }];
}

This is unexpected to me. Not sure if it is relevant, but what OS version are you running it on? — lindon fox, Sep 07 '12 at 03:57
Yes I met the same issue, parent-view's alpha **will change** if child-view's alpha changed, but child-view's alpha **won't change** if parent-view's alpha changed. — Mil0R3, Sep 07 '12 at 04:03
This question should help: http://stackoverflow.com/q/8346100/937822 — lnafziger, Sep 07 '12 at 04:27
I guess I am misunderstanding, if viewToFade contains the segmented control, it will disappear when it's parent alpha = 0.0. A view won't respond to touches when it's alpha=0.0 (or it's ancestors). But it's also not visible to touch. Am I mixed up on this? — danh, Sep 07 '12 at 04:43
@danh: The system considers the alpha to be 0 before the animation even starts. It does NOT gradually change the alpha. That is, after half the animation is done, the alpha is not 0.5. It will go from 1 to 0, no in-between values. — Scott Berrevoets, Sep 07 '12 at 06:05

score 1 · Answer 1 · answered Sep 07 '12 at 13:34

I played around with this in a sample project and could duplicate your results - nothing I did even animating (in my case) a button itself rendered it immune to touches. However in my limited test I was able to see that it did respond to highlighting.

I just tested the following (using a UIBuutton, suppose the same thing will work for segmented control):

add a transparent view over your button, and add a gesture recognizer to it, just before the animation
have the actionMethod of the tap recognizer change the highlighting of the button on, then dispatch a block to turn it off in 100ms or so (you could get fancier if you actually intercept touches).
in addition to changing the highlighting, send something like this to the control (again using a button) :
```
[tapButton sendActionsForControlEvents:UIControlEventTouchUpInside];
```

It appears the control is responsive to such things during the animation.

Oooh, this looks great! Unfortunately, I'm too much a newbie to know how to implement it--I don't understand blocks (I got the block code I used from the Apple documentation). I did find a solution to my problem (original question edited), but I suspect it's far less elegant than this. — Joel Derfner, Sep 07 '12 at 14:38
If its just blocks you are cannot deal with, you can use one of the 'performSelector' messages that has 'after' parameter. Otherwise, offer a bound of 50 pts to the person who codes this for you. You need to specify the number of segments, if they are momentary or selectable. — David H, Sep 07 '12 at 15:12

UISegmentedControl not responding within UIView

1 Answers1