UICollectionView reload data Issue - ios

I have a problem with data reloading using UICollectionView. I have this array on the viewDidLoad to fill the UICollectionView.
array = [[NSMutableArray alloc] init];
[array addObject:#"1"];
[array addObject:#"2"];
[array addObject:#"3"];
[array addObject:#"4"];
[array addObject:#"5"];
[array addObject:#"6"];
and the method:
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
NSString *cellIdentifier = #"Cell";
//cell = [[UICollectionViewCell alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
myCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];
UILabel *titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(5, 0, 100, 20)];
[titleLabel setText:[array objectAtIndex:indexPath.row]];
titleLabel.textColor = [UIColor whiteColor];
titleLabel.backgroundColor = [UIColor clearColor];
[cell addSubview:titleLabel];
return cell;
}
I tap the UIButton and data is reloaded:
[myCollectionView reloadData];
Here how the data looks like before and after the reload:

You add a new label each time you tap the reload button. You should add the label once and change the label text according.
Here a simple example.
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
MyCell *cell = (MyCell *)[collectionView dequeueReusableCellWithReuseIdentifier:#"Cell"
forIndexPath:indexPath];
[cell setMyTextLabel:indexPath.row];
return cell;
}
where MyCell will contains a UILabel and a property to modify its text.
I really suggest to take a look at Fun with UICollectionView code by #Ben Scheirman.
Hope that helps.
P.S. Rename myCell to MyCell. A class should start with an uppercase letter.

You are adding your label when you tap reload button. In that case you are adding label again and again...
So there are three solutions:
Make your cell reusable
Remove your cell from superview in reload method.
You can check if label's text length is not equal to zero. In that case no need to add that label and change text.

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:#"cellIdentifier" forIndexPath:indexPath];
dispatch_async(dispatch_get_main_queue(), ^{
// ********* Changed *******
for (UIView *v in [cell.contentView subviews])
[v removeFromSuperview];
// ********** Changed **********
if ([self.collectionviewFlow.indexPathsForVisibleItems containsObject:indexPath]) {
NSString *img_name=[NSString stringWithFormat:#"%#_thumb%d.png",self.VaritiesName,(int)indexPath.row+1];
imageVw=[[UIImageView alloc]initWithImage:[UIImage imageNamed: img_name]];
imageVw.frame=CGRectMake(10,10,100,100);
[cell.contentView addSubview:imageVw];
}
});
cell.backgroundColor=[UIColor clearColor];
return cell;
}

It is quit late, but here is my solution.
if you used custom collectionviewcell
try to use 'func prepareForReuse()'

Related

Single CollectionView for Multi Tab SegmentControl

I want to display two collection view using segment controller, on change of segment second collection view will display.
my code is :
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"morningcell" forIndexPath:indexPath];
UICollectionViewCell *cell1 = [collectionView dequeueReusableCellWithReuseIdentifier:#"eveningcell" forIndexPath:indexPath];
if (_segment.selectedSegmentIndex == 0) {
UILabel *lbl = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, cell.frame.size.height,cell.frame.size.width)];
lbl.text = [numbers objectAtIndex:indexPath.row];
[cell addSubview:lbl];
[lbl setTextAlignment:UITextAlignmentCenter];
return cell;
}
else{
UILabel *lbl = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, cell1.frame.size.height,cell1.frame.size.width)];
lbl.text = [numbers objectAtIndex:indexPath.row];
[cell1 addSubview:lbl];
[lbl setTextAlignment:UITextAlignmentCenter];
return cell1;
}}
Do not create two collectionView for the task that you want because you can achieve it using a single collectionView.
#interface YourVC(), UICollectionViewDelegate, UICollectionViewDataSource {
NSArray *arrayOfModelsForFirstCollectionView;
NSArray *arrayOfModelsForSecondCollectionView;
}
#end
#implementation YourVC
-(void)viewDidLoad{
[super viewDidLoad];
//Fetch Data For both Segments Using Your Web API Call or Local Database API Call
}
-(IBAction)didChangeSegmentIndex:(id)sender{
//When segment is changed you need to tell your collectionView to update the data.
[self.collectionView reloadData];
}
-(NSInteger) collectionView:(UICollectionView *)collectionView numberOfRowsInSection:(NSInteger)section{
//When reloadData is call this method will check that which index is selected.
//And according to selection it will create number of cells.
if (self.segmentControl.selectedIndex == 0){
return arrayOfModelsForFirstCollectionView.count;
}else{
return arrayOfModelsForSecondCollectionView.count;
}
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
//While creating a cell it will check which segment is selected so it will initialize and create the cell with respect to selection of segments.
//Hence you have created two different cells in a single collectionView toggling with a segmentControl.
if (_segment.selectedSegmentIndex == 0) {
return [self makeCellForFirstSegmentAtIndexPath: indexPath];
}
else{
return [self makeCellForSecondSegmentAtIndexPath: indexPath];
}
}
-(UITableViewCell *)makeCellForFirstSegmentAtIndexPath:(NSIndexPath *)indexPath{
//To show data from array you need to use arrayOfModelsForFirstCollectionView because this array is associated with First Segment Index
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"morningcell" forIndexPath:indexPath];
UILabel *lbl = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, cell.frame.size.height,cell.frame.size.width)];
lbl.text = [arrayOfModelsForFirstCollectionView objectAtIndex:indexPath.row];
[cell addSubview:lbl];
[lbl setTextAlignment:UITextAlignmentCenter];
return cell;
}
-(UITableViewCell *)makeCellForSecondSegmentAtIndexPath:(NSIndexPath *)indexPath{
//To show data from array you need to use arrayOfModelsForSecondCollectionView because this array is associated with Second Segment Index
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"eveningcell" forIndexPath:indexPath];
UILabel *lbl = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, cell.frame.size.height,cell.frame.size.width)];
lbl.text = [arrayOfModelsForSecondCollectionView objectAtIndex:indexPath.row];
[cell addSubview:lbl];
[lbl setTextAlignment:UITextAlignmentCenter];
return cell;
}
#end

collectionview just filling one cell

I'm trying to fill a collectionview with data from an array which I've checked it has the data, but at runtime it's filling just the cell at index 0.
The collectionview is a list of friends in pages of 9 items showing photo and name. The number of items at section is working properly, I mean, if the array has 3 objects, the collectionview displays three cells but just the first one with the photo and name of the object, concretly the last one in the array, not the first one. And the other cells show the prototype cell.
I guess I'm dealing wrong with the indexpath of the collection view, but I have another one in my storyboard and works properly. This other one has only one cell per page, could be something related to this?
I paste my collectionview methods:
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return [self.miListaAmigos count];
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
static NSString *CellIdentifier = #"friendCell";
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];
UILabel *nameLabel = (UILabel *)[self.view viewWithTag:102];
nameLabel.font = [UIFont fontWithName:#"Ubuntu" size:12.0];
nameLabel.text = [[self.miListaAmigos objectAtIndex:indexPath.row] valueForKey:#"usr_username"];
return cell;
}
you not directly reuse UILabel from self.view, UILabel *nameLabel = (UILabel *)[self.view viewWithTag:102];
try this below code for solve your problem:
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
static NSString *CellIdentifier = #"friendCell";
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];
if(cell == nil)
{
//Create UILabel here
UILabel *nameLabel=[[UILabel alloc]initWithFrame:CGRectMake(5, 5, 310, 20)];
nameLabel.tag=100;
[cell addSubview:nameLabel];
nameLabel.font = [UIFont fontWithName:#"Ubuntu" size:12.0];
}
// Access label and reuse
UILabel *nameLabel = (UILabel *)[cell viewWithTag:100];
nameLabel.text = [[self.miListaAmigos objectAtIndex:indexPath.row] valueForKey:#"usr_username"];
return cell;
}
Check your collectionView alloc and required deleagte:
UICollectionViewDelegate态UICollectionViewDataSource态 UICollectionViewDelegateFlowLayout.
e.g.
UICollectionViewFlowLayout *collectionLayout = [[UICollectionViewFlowLayout alloc] init];
[collectionLayout setScrollDirection:UICollectionViewScrollDirectionVertical];
UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:collectionLayout];
[collectionView registerClass:[CNCollectionViewCell class] forCellWithReuseIdentifier:cellIndetify];
collectionView.delegate = self;
collectionView.dataSource = self;
[self.view addSubview:collectionView];
Your label is in self.view not in the cell... You really should make a subclass of UICollectionViewCell
File -> New -> File -> Cocoa Touch Class
Class: MYFriendCollectionViewCell
Subclass of: UICollectionViewCell
Also Create XIB: Tick
Language: Objective C
Look at MYFriendCollectionViewCell.xib and make your label inside here... connect the labels to an IBOutlet... don't use tags...
#property (weak, nonatomic) IBOutlet UILabel *nameLabel;
https://www.youtube.com/watch?v=GusRijNLUGg <- connecting IBOutlets
Add the line below in your ViewController
[self.collectionView registerNib:[UINib nibWithNibName:#"MYFriendCollectionViewCell" bundle:nil] forCellWithReuseIdentifier: CellIdentifier];
Change your cellForItem to:
static NSString *CellIdentifier = #"friendCell";
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
cellForItemAtIndexPath:(NSIndexPath *)indexPath{
MYFriendCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier: CellIdentifier forIndexPath: indexPath];
cell.nameLabel.font = nameLabel.font = [UIFont fontWithName:#"Ubuntu" size:12.0]; // This ideally would be in MYFriendCollectionViewCell.m
cell.nameLabel.text = [[self.miListaAmigos objectAtIndex:indexPath.row] valueForKey:#"usr_username"];
return cell;
}

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];
}
}

UILabel In UICollectionViewCell is setting after scrolling?

In my code,I was trying to use UIImage & UIabel in UICollectionViewCell.What I was doing If there is no image in UICollectionViewCell i want to shift UILabel upwards.So I used two frames of label and checked for if(UIImageView.image==nil) it is showing effect after scrolling?
What to do?
Here is the code what i did-
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *myCell=(UICollectionViewCell*)[self.view viewWithTag:1];
myCell = [collectionView
dequeueReusableCellWithReuseIdentifier:#"Cell"
forIndexPath:indexPath];
UILabel *label=(UILabel*)[myCell viewWithTag:12];
UIImageView *collectionViewImage=(UIImageView*)[myCell viewWithTag:11];
NSString *collectionViewImageName=[imagesCollectionViewArray objectAtIndex:indexPath.row];
collectionViewImage.image=[UIImage imageNamed:collectionViewImageName];
if (collectionViewImage.image==nil) {
[collectionViewImage setBackgroundColor:[UIColor clearColor]];
[label setFrame:CGRectMake(35, 73, 309, 54)];
label.text=[lableColectionviewArray objectAtIndex:indexPath.row];
return myCell;
}else {
[label setFrame:CGRectMake(20, 294, 352, 49)];
label.text=[lableColectionviewArray objectAtIndex:indexPath.row];
return myCell;
}
}
Try to remove cell contentView subviews every collectionView
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
cellForItemAtIndexPath:(NSIndexPath *)indexPath
method call.
use
for([UIView *view in cell.contentView.subViews]){
[view removeFromSuperView];
view=nil;
}
and replace this line of code
UICollectionViewCell myCell=(UICollectionViewCell)[self.view viewWithTag:1];
With
UICollectionViewCell *myCell=nil;

Trouble with adding UILabel to UITableViewCell

I have some trouble with adding UILabel as subview to UITableViewCell. My code:
bookMarkTable=[[UITableView alloc]initWithFrame:CGRectMake(0, 50, 480, 270)];
bookMarkTable.rowHeight = 38.0f;
bookMarkTable.backgroundColor=[UIColor colorWithRed:247/255.0 green:246/255.0 blue:242/255.0 alpha:1];
[bookMarkTable setDelegate:self];
[bookMarkTable setDataSource:self];
[bookMarkMainView addSubview:bookMarkTable];
and UITableView delegate methods:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return bookMarksArray.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
// Configure the cell...
NSMutableDictionary* cellDictionary =[bookMarksArray objectAtIndex:indexPath.row];
UILabel* bookMarkTitle =[[UILabel alloc]initWithFrame:CGRectMake(50, 0, 370, 40)];
bookMarkTitle.text=[cellDictionary valueForKey:#"bm_title"];
bookMarkTitle.backgroundColor=[UIColor clearColor];
bookMarkTitle.font=[UIFont fontWithName:#"Georgia" size:20.0f];
[cell.contentView addSubview:bookMarkTitle];
return cell;
}
- (CGFloat) tableView: (UITableView *) tableView heightForRowAtIndexPath: (NSIndexPath *) indexPath{
return 38.0f;
}
I add rows via this method
-(void)addBookmark{
NSMutableDictionary* infoDict=[[NSMutableDictionary alloc]init];
NSString* bookmarkTitle=[NSString stringWithFormat:#"This is :[%i]",bookMarksArray.count];
[infoDict setValue:bookmarkTitle forKey:#"bm_title"];
[bookMarksArray addObject:infoDict];
[bookMarkTable reloadData];
}
But when i invoke this method multiply times it seems that all UILabel are added more than once. Here is a result
Any help is appreciated !
What's happening is that each time you move the table, the method is called and adds a new UILabel to the cell.
You should create a subclass of UITableViewCell and add the label there.
Other option, since you are just using one label, is to use the default label of UITableViewCell.
Change
UILabel* bookMarkTitle =[[UILabel alloc]initWithFrame:CGRectMake(50, 0, 370, 40)];
bookMarkTitle.text=[cellDictionary valueForKey:#"bm_title"];
bookMarkTitle.backgroundColor=[UIColor clearColor];
bookMarkTitle.font=[UIFont fontWithName:#"Georgia" size:20.0f];
[cell.contentView addSubview:bookMarkTitle];
to
cell.textLabel.text = [cellDictionary valueForKey:#"bm_title"];
At the begin from - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath you must remove the subviews.
for(UIView* vista in cell.contentView){
[vista removeFromSuperview];
}
And that's all.
PD: Check if the removed view is the correct.
Try to change:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
with:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:nil];

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