Do gesture recognizers retain the target?

[Simon Harris]

I noticed a bunch of code I have that removes gesture recognizers in viewWillDisappear. I can't recall why I did it but I'm wondering if it was in order to avoid a retain cycle. Now I'm questioning if that could even be possible. Is it necessary to remove gesture recognizers? Do they in fact retain their targets?

Thanks,

Simon

[Chris Miles]

Hi Simon,

A view retains any gesture recognizers added to it. The gesture recognizers do not retain the views. Although they provide a reference to the view they were added to.

When a view is dealloc'd I would expect it to release any added gesture recognizers.

I don't see a reason to explicitly remove the gesture recognizers in viewWillDisappear, unless they are being added in a related method like viewWillAppear and the developer was ensuring that duplicate recognizers were not being added to views.

Cheers,
Chris

[Simon Harris]

Hi Chris,

Thanks for responding so quickly.

On 14/05/2012, at 11:13 AM, Chris Miles wrote:

> Hi Simon,
>
> A view retains any gesture recognizers added to it. The gesture recognizers do not retain the views. Although they provide a reference to the view they were added to.

I was also interested if the targets were retained but if they are release by the view then that wouldn't be a problem anyway, I guess.

> I don't see a reason to explicitly remove the gesture recognizers in viewWillDisappear, unless they are being added in a related method like viewWillAppear and the developer was ensuring that duplicate recognizers were not being added to views.

Right, I am adding them in viewWillAppear but again, I'm not exactly sure why I did it that way. I suspect I just blindly copied an apple example way back when I was first learning this stuff.

[Chris Miles]

Hi Simon,

On 14/05/2012, at 11:17 AM, Simon Harris wrote:

>> I don't see a reason to explicitly remove the gesture recognizers in viewWillDisappear, unless they are being added in a related method like viewWillAppear and the developer was ensuring that duplicate recognizers were not being added to views.
>
> Right, I am adding them in viewWillAppear but again, I'm not exactly sure why I did it that way. I suspect I just blindly copied an apple example way back when I was first learning this stuff.

I can't think of any specific reason to implement that strategy over adding recognizers in viewDidLoad, for example. Other than for a more aggressive memory saving strategy. On the other hand, there's nothing wrong with it if it is working for you.

Cheers,
Chris

[Simon Harris]

>>> I don't see a reason to explicitly remove the gesture recognizers in viewWillDisappear, unless they are being added in a related method like viewWillAppear and the developer was ensuring that duplicate recognizers were not being added to views.
>>
>> Right, I am adding them in viewWillAppear but again, I'm not exactly sure why I did it that way. I suspect I just blindly copied an apple example way back when I was first learning this stuff.
>
> I can't think of any specific reason to implement that strategy over adding recognizers in viewDidLoad, for example. Other than for a more aggressive memory saving strategy. On the other hand, there's nothing wrong with it if it is working for you.

OK, thanks Chris