Question

I’ve made my own custom photo gallery control, where the user can tap a photo to be taken to a larger version, or any other action you want.

I want this done so that the UIViewController holding this gallery contains the selectors, e.g

- (IBAction)photoThumbnailClicked(id)sender
{
    // Enlarge the photo here
}

I’d want to somehow keep a reference of the view controller and selector in the photo gallery object, so when each photo thumbnail button is generated, the targets can be set like this:

[thumbnail addTarget:self.target
                   action:self.action
         forControlEvents:UIControlEventTouchUpInside];

I’m currently keeping the references like this, although I’m not sure it’s the best way as I have reason to believe there may be memory issues:

PhotoGallery.h:

@interface PhotoGallery : UIScrollView

@property UIViewController *target;
@property SEL action;

- (void)setTarget:(UIViewController*)viewController
     withAction:(SEL)action;
@end

setTarget method in PhotoGallery.m:

- (void)setTarget:(UIViewController*)target withAction:(SEL)action
{
    self.target = target;
    self.action = action;
}

Is this the best way of doing this? If not, what should I do instead?

Thanks in advance for any help!

Answer 1

I’ve assumed ARC

IF your view hierarchy looks like this:

someViewControllerOrView   <------------|
       -                                |
  <any number of views>                 |
            -                           |
        photoGalleryInstance            |
                             -target ----

Then you probably want your target to be a weak reference otherwise you will probably encounter a “retain cycle”. That is someViewController holds on to photoGalleryInstance and photoGalleryInstance holds on to someViewController and neither is ever released.

@property (weak) UIViewController *target;
//or @property (unsafe_unretained) UIViewController *target; if target is < 5.0

Otherwise, your code looks like the standard way of implementing this pattern.