Get correct button from custom UICollectionViewCell - objective-c

Question

I have a custom UICollectionView with custom UICollectionViewCell, I have a like button on my cell (that has been connected to the CustomCVCell.h file) and I need to change the background of this button when it gets pressed. What I did was declaring the action for the button on the cellForItemAtIndexPath: method like this:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
// Configure the cell
FolderProducts *item = _feedItems[indexPath.item];
[cell.like addTarget:self action:#selector(likeProduct:) forControlEvents:UIControlEventTouchUpInside];
return cell;
}
Then on the button action I tried to change the background like this:
- (void)likeProduct:(UIButton *)button {
[button setImage:[UIImage imageNamed:#"dislike.png"] forState:UIControlStateNormal];
}
It works but then other random cell's like button has their image changed and I can't understand why..
I also tried to retrieve the correct cell by using:
CollectionViewCell *cell = (CollectionViewCell *)button.superview.superview;
And then:
[button setImage:[UIImage imageNamed:#"dislike.png"] forState:UIControlStateNormal];
But the result is still wrong

Answer 1

the problem is due to reusing of the collection view cell because of this u are getting the random button having the same image
the solution for this would be maintaining the array and storing the selected index paths of the liked button
for example u can do like below
Define a custom deleagte in CustomCVCell.h
#import <UIKit/UIKit.h>
#class CustomCVCell; //forword decleration
#protocol CustomCellDelegate <NSObject>
- (void)customCell:(CustomCVCell *)cell actionForButton:(UIButton *)inButton; //hear u are passing the cell and the button
#end
#interface CustomCVCell : UICollectionViewCell
#property (weak, nonatomic) IBOutlet UIButton *like ; //a button with outlet
#property (weak, nonatomic) id<CustomCellDelegate> cellDelegate;// define a custom delegate
- (IBAction)likeProduct:(UIButton *)sender; // set action to cell not in the controller
//... other code
#end
and in CustomCVCell.m
#import "CustomCVCell.h"
#implementation CustomCVCell
- (id)initWithFrame:(CGRect)frame
{
self = [CustomCVCell cell];
if (self)
{
}
return self;
}
- (void)awakeFromNib {
// Initialization code
}
//handle button action in the cell
- (IBAction)likeProduct:(UIButton *)sender
{
//this action you want it to be in controller, call a delegate method
if([self.cellDelegate respondsToSelector:#selector(customCell:actionForButton:)])
{
[self.cellDelegate customCell:self actionForButton:sender]; //implent the action in the controller
}
}
#end
and in controller
- (void)viewDidLoad
{
[super viewDidLoad];
UICollectionViewFlowLayout *aFlowLayout = [[UICollectionViewFlowLayout alloc]init];
//..set up code
[_aCollectionView registerClass:[CustomCVCell class] forCellWithReuseIdentifier:#"CELL"];
likedCells = [[NSMutableArray alloc]init]; //to hold the index paths of the liked cells
}
//..other code
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
CustomCVCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"CELL" forIndexPath:indexPath];
if([likedCells containsObject:indexPath]) //based on the indexaths paths u can set the images of the liked cell and if not set nil
{
[cell.like setBackgroundImage:[UIImage imageNamed:#"22.jpg"] forState:UIControlStateNormal];
}
else
{
[cell.like setBackgroundImage:nil forState:UIControlStateNormal];
}
cell.backgroundColor = [UIColor greenColor]; //for testing
cell.cellDelegate = self; //this must be important
return cell;
}
//as the like button cliks this method will trigger since u are passing the cell and the button, u can get the index path of the cell
- (void)customCell:(CustomCVCell *)cell actionForButton:(UIButton *)inButton
{
//hear u will get both cell and its button
//[inButton setImage:[UIImage imageNamed:#"22.jpg"] forState:UIControlStateNormal];
[inButton setBackgroundImage:[UIImage imageNamed:#"22.jpg"] forState:UIControlStateNormal]; //set the image
[likedCells addObject: [_aCollectionView indexPathForCell:cell]]; //and store the index path in the likedCells array
}
that's it if u want reverse the action same remove the index path

Answer 2

The basic idea is that you need to convert the buttons coordinate space to the collection views coordinate space and then retrieve the indexPath.
If you need to use Objective-C, lets create a function that returns the indexPath of a given cell's subview:
- (NSIndexPath *)indexPathForCellContainingView:(UIView *)view inCollectionView:(UICollectionView *)collectionView {
CGPoint viewCenterRelativeToCollectionView = [collectionView convertPoint:CGPointMake(CGRectGetMidX(view.bounds), CGRectGetMidY(view.bounds)) fromView:view];
NSIndexPath *cellIndexPath = [collectionView indexPathForItemAtPoint:viewCenterRelativeToCollectionView];
return cellIndexPath
}
Now in your button handler:
- (void)likeProduct:(UIButton *)button {
[button setImage:[UIImage imageNamed:#"dislike.png"] forState:UIControlStateNormal];
NSIndexPath *buttonIndexPath = [self indexPathForCellContainingView:button];
UICollectionViewCell *tappedCell = [collectionView cellForItemAtIndexPath:buttonIndexPath];
}
Remember, your cell will be reused when it scrolls out of bounds so you definitely need to keep track of this state. Either you persist it to disk or you have a simple NSDictionary that manages the state of each button.
I have a convenient Gist in Swift that solves exactly that for UICollectionView and UITableView as well.
There are similar questions here and here

Answer 3

Assign a tag to your button to identify it.
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
// Configure the cell
FolderProducts *item = _feedItems[indexPath.item];
[cell.like addTarget:self action:#selector(likeProduct:) forControlEvents:UIControlEventTouchUpInside];
cell.like.tag = indexPath.item;
return cell;
}
Then in the implementation method add below code,
- (void)likeProduct:(UIButton *)button {
UIButton *btn = (UIButton *)sender;
[button setImage:[UIImage imageNamed:#"dislike.png"] forState:UIControlStateNormal];
}
Note : The best way to achieve multiple/single selection is via id associated with your likes. Store that id using collection view then after reload the table from the button method.
Let me know if you still need more help..

Answer 4

You can set tag of button & retrieve tag in your selector.
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
// Configure the cell
FolderProducts *item = _feedItems[indexPath.item];
cell.like.tag = indexPath.item
[cell.like addTarget:self action:#selector(likeProduct:) forControlEvents:UIControlEventTouchUpInside];
return cell;
}

Answer 5

because your not setting tag for your buttons in cell. So these all are selected at once. You can set their tag like indexPath.item and catch their tag in didSelectItemAtIndexPath and select the desired item.