Re: Setting the Selected Segment of a Segmented Control
Re: Setting the Selected Segment of a Segmented Control
- Subject: Re: Setting the Selected Segment of a Segmented Control
- From: Keary Suska <email@hidden>
- Date: Wed, 15 Oct 2014 10:00:43 -0600
On Oct 15, 2014, at 9:46 AM, Daniel Blakemore <email@hidden> wrote:
> I can understand that it might behave that way. It's not in and of itself
> unreasonable, although in my opinion if the selected segment changes
> visually, it's kind of weird not to send the message since the key isn't
> UIControlEventValueChangedButReallyIOnlyCareAboutWhenTheChangeCameFromATouch.
>
> The irksome thing is that it used to work and now doesn't and there's no
> API diff around selectedSegment and the wording in the documentation didn't
> change between iOS 7 and 8.
>
> So I don't know if it's an intentional decision or an oversight.
The docs say,
UIControlEventValueChanged
A touch dragging or otherwise manipulating a control, causing it to emit a series of different values.
So, it seems documented to only trigger on a touch event, so it is possible that the behavior you had in iOS 7 was unintentional, since there is also no mention in release notes of change of behavior.
It is also useful to know that "event" handling almost exclusively relate to device input, not to programmatic changes. I.e., setting the value of a control is not an "event" so no event handling will get involved. You certainly could cause an event to programmatically fire…
So the main issue is that you are using an event handling method incorrectly to begin with...
> On Tue, Oct 14, 2014 at 9:20 PM, Richard Charles <email@hidden>
> wrote:
>
>> Not sure about iOS but on OS X programmatically calling
>>
>> [NSSegmentedControl setSelectedSegment:]
>>
>> does not trigger the target / action message.
>>
>> You need to programmatically respond after setting the selected segment.
>>
>> Richard Charles
>>
>> On Oct 14, 2014, at 6:55 PM, Daniel Blakemore <email@hidden>
>> wrote:
>>
>>> I have a simple problem. I am programmatically setting the selected
>>> segment of a segmented control. Then the segmented control is changing
>>> which segment appears selected on screen.
>>>
>>> You might be saying to yourself, "this seems correct". You would also be
>>> correct.
>>>
>>> What is incorrect is that while the control *appears* to have changed, my
>>> code knows nothing of this.
>>>
>>> I have an action added for the control event UIControlEventValueChanged
>>> which is called as expected when you tap the control.
>>>
>>> HOWEVER, when changing the control programmatically, no such event is
>>> generated. This leaves my app in an inconsistent state.
>>>
>>> For reference, see this example project
>>> https://github.com/danblakemore/SegmentedNope.
>>>
>>> This worked in iOS 7. It now does not. What has changed?
>>>
>>> --
>>> Daniel Blakemore
>>> Pixio Software
>>> _______________________________________________
>>
>>
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Keary Suska
Esoteritech, Inc.
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