Access the UICollectionViewCell Components in custom method - ios

Question

I have some components in UICollectionViewCell and i can access all inside the cellForItemAtIndexPath. I need to access the component in a custom method,
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
// UIButton
cell.btn1.frame =CGRectMake(380,100, 150, 40);
[cell.btn1 addTarget:self action:#selector(btnClicked) forControlEvents:UIControlEventTouchUpInside];
return cell;
}
In custom method,
-(void)btnClicked{
MycollectionclassView *cell =[[MycollectionclassView alloc]init];
cell.btn1.backgroundColor =[UIColor greenColor];
}
Here I cannot change the color of the button.

Answer 1

You must create a protocol and create a IBAction to a method. When your action method is called, you can notify the protocol and its screen that has the UICollectionView protocol will receive this event.
On your cell header file.h define the protocol:
#protocol YourCellNamelDelegate <NSObject>
#required
/**
* Notifies that current ITEM was clicked on icon.
*
* #param cell The current cell that was clicked.
*/
-(void)bookmarkClicked:(YourCellName *)cell; // OR without argument
#interface YourCellName : UITableViewCell
/**
* Reference to 'YourCellNameDelegate' delegate.
*/
#property (assign,nonatomic) id<YourCellNamelDelegate>delegate;
...
On your cell file.m
...
- (IBAction)bookmarkClickAction:(id)sender {
// change or update screen element here ...
if (self.delegate) {
[self.delegate bookmarkClicked:self];
}
}
On your ViewController implement the your protocol
#interface SMGListViewController () <YourCellNameDelegate>
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
// get your cell here, for example in my case:
SMGCityGuideCollectionViewCell *cell;
cell = (SMGCityGuideCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
SMGTouristInfo *touristInfo = [self.listTouristInfo objectAtIndex:indexPath.row];
[cell setTouristInfoCell:touristInfo];
// IMPORTANT HERE *************************
cell.delegate = self;
// IMPORTANT HERE *************************
return cell;
}
...
#pragma mark <SMGPlaceCellDelegate>
-(void)bookmarkClicked:(SMGPlaceCell *)cell {
// notify events here ...
NSIndexPath *index = [self.tableViewPlaces indexPathForCell:cell];
[self.tableViewPlaces reloadRowsAtIndexPaths:#[index] withRowAnimation:UITableViewRowAnimationAutomatic];
}
I hope it helps! :)

Answer 2

To make things clear , when cellForItemAtIndexPath gets called it is the time that your cells get laid in the view , in your custom method you are just creating a cell object but this object does not reference the objects that is laid out in your collection view , so your just changing the color of a newly created object that does not reference anything .

Answer 3

In the Button Click function pass arguments as Sender , by which in the function call you can access the collectionView cell as Sender.SuperView .
You can also find the indexpath from the collectionviewcell now.
Now if you want to update a UI of the Collection view cell , you will have to do it in the cellforItemAtIndexPath function. which can be called by [collectionview reloadData].
So I would suggest to keep some flag variable in the data source to check if you have to update the UI or not.