how to access from UICollectionViewCell the indexPath of the Cell in UICollectionView

Question

i want to animate the UICollectionViewCell when action is called.
i have done UICollectionViewCell in Interface Builder, the UICollectionView also. Now i want to get the correct indexPath at my actionBtnAddToCard method.

thats the way i try it now (method in ProduktViewCell.m):

- (IBAction)actionAddToCart:(id)sender {
    XLog(@"");

    // see this line
    NSIndexPath *indexPath = ??** how can i access the correct indexPath**??;
    SortimentViewController *svc = [[SortimentViewController alloc] initWithNibName:@"SortimentViewController_iPad" bundle:[NSBundle mainBundle]];
    [svc.collectionViewProdukte cellForItemAtIndexPath:indexPath];

    [svc collectionView:svc.collectionViewProdukte didSelectItemAtIndexPath:indexPath];
} 

SortimentViewController is the viewController which inherits the UICollectionView.
how to acces the correct indexPath?

UPDATE 1: edited post for better understanding.

Solution 1

if you know the view hierarchy it is easy.

UIButton *button = (UiButton *) sender;

if the button is like this - > UITableViewCell - > button

then you can get cell like this

UITableViewCell *cell = (UITableViewCell *)[button superview];

if the button is like this - > UITableViewCell - > content view -> button

UITableViewCell *cell = (UITableViewCell *)[[button superview] superview];

and finally index path can be extracted like this

NSIndexPath *indexPath = [self.table_View indexPathForCell:cell];

Solution 2

- (IBAction)actionAddToCart:(id)sender {
   NSIndexPath *indexPath;
   indexPath = [self.collectionView indexPathForItemAtPoint:[self.collectionView convertPoint:sender.center fromView:sender.superview]]; 
   ...
}

Solution 3

Do Not Depend on view. Try this.

CGPoint buttonPosition = [sender convertPoint:CGPointZero toView:self.collectionView];
NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:buttonPosition];

NSLog(@"%ld", (long)indexPath.row);

Solution 4

Using code like [[button superview] superview] is fragile and not future-proof; indeed, it's not even guaranteed to work on all iOS versions unless you explicitly test it. I always use an iterative helper method for this purpose:-

- (UIView *)superviewWithClassName:(NSString *)className fromView:(UIView *)view
{
    while (view)
    {
        if ([NSStringFromClass([view class]) isEqualToString:className])
        {
            return view;
        }
        view = view.superview;
    }
    return nil;
}

Then I call it from the button handler like so:-

- (IBAction)buttonClicked:(id)sender
{
    UIButton *button = (UIButton *)sender;
    UICollectionViewCell *cell = (UICollectionViewCell *)
                                [self superviewWithClassName:@"UICollectionViewCell"
                                fromView:button];
    if (cell)
    {
        NSIndexPath *indexPath = [self.collectionView indexPathForCell:cell];
        // do whatever action you need with the indexPath...
    }
}

UPDATE: Swift version of superviewWithClassName. Made it a class method since it never references self.

static func superviewWithClassName(className:String, fromView view:UIView?) -> UIView? {
    guard let classType = NSClassFromString(className) else {
        return nil
    }
    var v:UIView? = view
    while (v != nil) {
        if v!.isKindOfClass(classType) {
            return v
        }
        v = v!.superview
    }
    return nil
}

and some code to call it, either from prepareForSegue or a button handler:-

guard let cell = UIView.superviewWithClassName("UICollectionViewCell", fromView: sender as? UIView) as? UITableViewCell else {return}

Solution 5

Swift solution: A UICollectionView extension like this one can be useful for this.

extension UICollectionView {
    func indexPathForView(view: AnyObject) -> NSIndexPath? {
        let originInCollectioView = self.convertPoint(CGPointZero, fromView: (view as! UIView))
        return self.indexPathForItemAtPoint(originInCollectioView)
    }
}

Usage becomes easy everywhere.

let indexPath = collectionView.indexPathForView(button)

View more solutions

Comments

[brush51]

but how can i get the indexPath? i will update my question for better understanding

[Tim]

An indexPath is just a way to refer to a specific cell. Without knowing what your app does, I have no way to guess which cell you are trying to animate.

[Tim]

To get the first cell, it would be something like this: NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:0];

[brush51]

thats my problem. How can i find out on which cells action is called?

[Tim]

That really depends on the structure of your app. If each cell has an 'add to cart' button, you might think about putting that button inside the cell (which should be a UICollectionViewCell subclass), and make sure the button is calling a method on the cell itself (not the view controller). Then use a delegation pattern to call some logical method on the view controller: something like -(void)addToCartButtonPressedForCell:(UICollectionViewCell *)cell];

[ChuckKelly]

yeah , bit confused what u mean when talking in the context of a collection view, would you mind shoing us a full action snippet?

[iSeeker]

The OP had asked for a solution in the case for UICollectionView not UITableViewCell.. IMHO this answer sends the wrong message to readers.. Please edit to point how to do this in UICollectionView.

[MickyD]

Consider adding an explanation

[Echelon]

[[button superview] superview] is fragile. I added a safer answer below.

[lee]

UITableViewCell *cell = (UITableViewCell *)[[button superview] superview]; help me.when I have: button->collectionview->UItableviewcell

[Bryan Bryce]

This works until you enable reordering of items, then you have to manually go in and fix indexPath property for all the affected cells.

[Brian Sachetta]

Sorry but calling superview a bunch of times is very hacky. Changes to the view hierarchy could easily break such calls. And this original question does not deal with UITableView.

[Brian Sachetta]

UICollectionView supports the indexPathForCell: method as well. If you update this answer to reference UICollectionView / UICollectionViewCell rather than UITableView / UITableViewCell I will upvote.

[tuandapen]

Good solution. Thanks

[iRon3.0]

superview of a superview is a dangerous hack. i know because i use it 😂