How do I add a counter to a cell in UICollectionView cells? - ios

I have the following code:
- (UICollectionViewCell *) collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"cellIdentifier" forIndexPath:indexPath];
cell.backgroundColor = [UIColor whiteColor];
return cell;
}
How do I add a counter to dispaly in my cell that shows the number of the cell in the order it was created? Like cell 1 would say 1, 2 is 2, and so on.

Create a subclass of UICollectionViewCell. Add the counter (maybe just a label?) in the init method of the cell. Register you class for a cell identifier of your wish
[self.collectionView registerClass:[MyCollectionViewCell class]
forCellWithReuseIdentifier:#"myCellIdentifier"];
and dequeue the cell with the identifier. Then set the label value.
- (UICollectionViewCell *) collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
MyCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"myCellIdentifier" forIndexPath:indexPath];
cell.backgroundColor = [UIColor whiteColor];
cell.counterLabel.text = [NSString stringWithFormat:#"%d", indexPath.row];
return cell;
}

Related

how to use Two CollectionViewCell in the same CollectionViewController?

I would like to use two CollectionViewCell in the same CollectionViewController.
Can you help me please ?
thanks
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
// Configure the cell
cell.textLabel.text = [NSString stringWithFormat:#"%li", (long)indexPath.row + 1];
return cell;
}
Give each cell type a unique reuse identifier and, if necessary, a custom subclass of UICollectionViewCell. In your cellForItemAtPath function, use the identifier to get the one that's appropriate for the path, e.g.
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.item % 2 == 0) {
EvenCollectionViewCell *cell = (EvenCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier: "evenCell" forIndexPath :indexPath];
// Configure the cell
...
return cell;
} else {
OddCollectionViewCell *cell = (OddCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier: "oddCell" forIndexPath: indexPath];
// Configure the cell
...
return cell;
}
}

UICollectionView does not stay selected after scrolling

When I select a cell, it turns blue, which is good. Then when I scroll up and the cell out of view, it turns back to original color. Not sure how to fix this.
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:#"cellIdentifier" forIndexPath:indexPath];
cell.backgroundColor=[UIColor lightGrayColor];
[collectionView selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone];
self.collectionView.allowsMultipleSelection=YES;
return cell;
}
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *datasetCell =[collectionView cellForItemAtIndexPath:indexPath];
datasetCell.backgroundColor = [UIColor blueColor];
}
-(void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *datasetCell =[collectionView cellForItemAtIndexPath:indexPath];
}
In your first method, you are practically telling the collection view to select any cell that it asks for. Instead, you should check whether the cell you return has the same path as the selected one, and only then give it color:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:#"cellIdentifier" forIndexPath:indexPath];
if ([indexPath isEqual:self.selectedIndexPath]) // you need to create selectedIndexPath as a property
{
cell.backgroundColor=[UIColor blueColor];
}
else
{
cell.backgroundColor=[UIColor lightGrayColor];
}
return cell;
}
And then:
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
self.selectedIndexPath = indexPath;
}
When cell are reused, the selection state is lost. So you need to save the indexPath of the selection in didSelectItemAtIndexPath. And when you dequeue the cell you need to check and restore the state

UICollectionViewCell background color change works in cellForItemAtIndexPath but not didSelectItemAtIndexPath

I can change my collection view cell background color in cellforitematindexpath but not in didselectitematindexpath using the code below (i only change the color in one place however). How does this happen? I know that didselectitematindexpath is being called.
- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath {
CollectionViewCell *cell = [cv dequeueReusableCellWithReuseIdentifier:#"CollectionView" forIndexPath:indexPath];
cell.layer.borderWidth=1.0f;
cell.layer.borderColor=[UIColor grayColor].CGColor;
cell.label.text = #"test"
cell.contentView.backgroundColor = [UIColor redColor];
return cell;
}
-(void)collectionView:(UICollectionView *)cv didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"selected cell");
CollectionViewCell *cell = [self collectionView:cv cellForItemAtIndexPath:indexPath];
cell.contentView.backgroundColor = [UIColor redColor];
}
Several things wrong here.
You're using the wrong method to get the selected cell. Never call the delegate method directly, instead ask the collection view for the cell directly like this:
CollectionViewCell *cell = [cv cellForItemAtIndexPath:indexPath];
You're modifying the cell in a place where those modifications will not persist. When you scroll and that cell gets reused, the color will get wiped out. Instead you should call reloadItemsAtIndexPaths: when the cell gets selected, and have some code in collectionView:cellForRowAtIndexPath that checks the selected property of the cell and sets the color you want based on that. That way, the layout will remain consistent when you scroll and cells are reused.
use this..
self.collectionView.allowsMultipleSelection = YES;
then..
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath**
{
static NSString *identifier = #"Cell";
RecipeViewCell *cell = (RecipeViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
UIImageView *recipeImageView = (UIImageView *)[cell viewWithTag:100];
recipeImageView.image = [UIImage imageNamed:[recipeImages[indexPath.section] objectAtIndex:indexPath.row]];
cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"photo-frame-2.png"]];
cell.selectedBackgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"photo-frame.png"]];
return cell;
}
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
if (shareEnabled) {
NSString *selectedRecipe = [recipeImages[indexPath.section] objectAtIndex:indexPath.row];
[selectedRecipes addObject:selectedRecipe];
}
}
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath
{
if (shareEnabled) {
NSString *deSelectedRecipe = [recipeImages[indexPath.section] objectAtIndex:indexPath.row];
[selectedRecipes removeObject:deSelectedRecipe];
}
}

Reusing cell causes unwanted behaviour when updating cell view

I want ot set a border to a selected cell, i save a cell property that represents the selected one and manipulate it:
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
NSArray *eyeArray = [self eyesArrayConfigure][indexPath.row];
if (indexPath.row==5) {
int r = arc4random() % 6;
eyeArray = [self eyesArrayConfigure][r];
}
[borderedCell.contentView.layer setBorderWidth:0.0f] ;
UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
borderedCell = cell;
[borderedCell.contentView.layer setBorderColor:self.view.tintColor.CGColor];
[borderedCell.contentView.layer setBorderWidth:3.0f];
}
and the cellForView: (Im usinng 2 types of cell identifiers because one cell contains a label - "Random cell":
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.row ==5) {
UICollectionViewCell *randomCell =[collectionView
dequeueReusableCellWithReuseIdentifier:#"randomCell"
forIndexPath:indexPath];
randomCell.backgroundColor = [UIColor purpleColor];
borderedCell = randomCell;
[borderedCell.contentView.layer setBorderColor:self.view.tintColor.CGColor];
[borderedCell.contentView.layer setBorderWidth:3.0f];
return randomCell;
}
UICollectionViewCell *myCell = [collectionView dequeueReusableCellWithReuseIdentifier:#"cell" forIndexPath:indexPath];
NSArray *eyeArray = [self eyesArrayConfigure][indexPath.row];
myCell.backgroundView = [[UIImageView alloc] initWithImage:eyeArray[1]];
return myCell;
}
What i get is if a click one cell it will be fine till i scroll and then i get weird behaviour when couple of cells might be with the border.
Thanks for the help.
The solution is to use a view model. You are already doing this for your cells' background views. Apply the same concept for the border.
#interface MyCollectionView ()
#property (nonatomic) NSInteger selectedRow;
#end
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
//update self.selectedRow and either reload entire collection view or just the currently selected and previously selected.
self.selectedRow = indexPath.row;
[collectionView reloadData];
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *myCell = [collectionView dequeueReusableCellWithReuseIdentifier:#"cell" forIndexPath:indexPath];
CGFloat borderWidth = (indexPath.row == self.selectedRow) ? 3.0 : 0.0;
[myCell.contentView.layer setBorderWidth:borderWidth];
return myCell;
}

UICollectionView cell is not getting added as a subview of UICollectionView

I am new to UICollectionView.
I have followed this tutorial to learn how to use a UICollectionView, but the problem is that in the .xib (not using storyboard) I am not able to add UICollectionViewCell as a subview of UICollectionView.
In the tutorial the cell is automatically created under UICollectionView in the .xib.
Any help would be appreciated.
That tutorial is for working in stroy board in xib you ve to create custom cell first create view controller add UicollectionView to view Controller
then create custom class for collection cell
then craete empty xib resource and add collection view cell
and set class name and identifier for that control
then create delegates method to add custom cell to ur collectionViewController
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
static NSString *cellIdentifier = #"customCell";
customCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];
return cell;
}
You can start your controller and create a custom collection view cell for setting your view element and then you can use it into your collection view controller into xib, here is a good tutorials to do this http://adoptioncurve.net/archives/2012/09/a-simple-uicollectionview-tutorial/
Use this code for creation of collectionview and adding the subview.
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return [imageArray count];
}
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
NSMutableArray *sectionArray = [imageArray objectAtIndex:section];
return [sectionArray count];
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
// Setup cell identifier
static NSString *cellIdentifier = #"cvCell";
/* Uncomment this block to use nib-based cells */
// UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];
// UILabel *titleLabel = (UILabel *)[cell viewWithTag:100];
// [titleLabel setText:cellData];
/* end of nib-based cell block */
/* Uncomment this block to use subclass-based cells */
CVCell *cell = (CVCell *)[collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];
NSMutableArray *data = [imageArray objectAtIndex:indexPath.section];
NSString *cellData = [data objectAtIndex:indexPath.row];
[cell.titleLabel setText:cellData];
cell.imageView.image = [UIImage imageNamed:[imageArray[indexPath.section] objectAtIndex:indexPath.row]];
return cell;
}
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
header *sectionHeader;
if (kind == UICollectionElementKindSectionHeader)
{
sectionHeader = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:#"Hello" forIndexPath:indexPath];
}
UICollectionReusableView *test=[collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:#"Hello" forIndexPath:indexPath];
return test;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
{
if (section == 3) {
return CGSizeMake(0, 100);
}
return CGSizeZero;
}
- (NSString *)applicationDocumentsDirectory {
return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
return CGSizeMake(80, 80);
}

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