Hello everyone I have a problem with the selection of cells in my collection.
To manage the selection and deselection, of course, I have provided the delegated methods didSelectItemAtIndexPath and didDeselectItemAtIndexPath
Everything works correctly but I have a problem that I can not solve. In short, when I selected a cell I would like to have the possibility to deselect the last cell selected by reselecting the cell itself ... for example
I will use a name for the cell to make you understand my problem better
The user selects the cell "22" to deselect it. I would like the user to reselect cell 22 again and deselect it.
I tried to use allowMultipleSelection = YES and this seems to be in the system that I prefer but the problem is that the cell is not reselected, all the other entries selected and so it is wrong ... How can I solve this problem ... ??
This is the code I utilize for select and deselect the cell
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
SmartCalendarDayCell *calendarDayCell = (SmartCalendarDayCell *)[self.dayCollectionView cellForItemAtIndexPath:indexPath];
calendarDayCell.day.textColor = [UIColor colorWithHexString:#"#D97E66" setAlpha:1];
}
-(void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
SmartCalendarDayCell *calendarDayCell = (SmartCalendarDayCell *)[self.dayCollectionView cellForItemAtIndexPath:indexPath];
calendarDayCell.day.textColor = [UIColor lightGrayColor];
}
As I understand, you want your collectionView can only select 1 cell at a time and if selected cell is clicked again, it will be deselected. If I'm misunderstanding anything, please tell me.
First
You shouldn't change textColor of day in didSelectItemAtIndexPath and didDeselectItemAtIndexPath methods. Because when you scroll collectionView, cells will be reused and color of day will be wrong for some cells.
To resolve it, using property selected of UICollectionViewCell.
SmartCalendarDayCell.m
- (void)setSelected:(BOOL)selected {
[super setSelected:selected];
if (selected) {
self.day.textColor = [UIColor colorWithHexString:#"#D97E66" setAlpha:1];
} else {
self.day.textColor = [UIColor lightGrayColor];
}
}
Second
To deselect selected cell, you should check and do it on collectionView:shouldSelectItemAtIndexPath: method.
- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath {
if ([collectionView.indexPathsForSelectedItems containsObject:indexPath]) {
[collectionView deselectItemAtIndexPath:indexPath animated:NO];
return NO;
}
return YES;
}
For more detail, you can check my demo repo here.
Related
I want to call didSelectItemAtIndexPath: for particular index path but I can't call it programmatically in cellForItemAtIndexPath because collection is not yet ready, I will get cell as nil. Do we have any delegate method or any other UIView method that is called after collection view is ready?
I have tried willDisplayCell: but it is not made for relevant work, couldn't find anything else.
I want to call didSelectItemAtIndexPath:
Don't. This is a delegate method. It is called by the runtime when the user selects an item. You must never call this yourself.
You have to do it programmatically utilising your manual logics. :)
The underlying concept is that get the indexes of selected cells and reload those specific cells only.
Declare a global var
NSMutableArray array_indexpath;
in your did select method add indexes of selected cells.
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
array_indexpath=[[NSMutableArray alloc]init];
[array_indexpath addObject:indexPath];
[self.myCollectionView reloadItemsAtIndexPaths:array_indexpath];
}
and in your cell for cellForItemAtIndexPath method check the indexes and reload it as required.
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
ShubhCalendarCollectionViewCell *cell =[collectionView dequeueReusableCellWithReuseIdentifier:#"ShubhCalendarCollectionViewCell" forIndexPath:indexPath];
cell.backgroundColor=[UIColor clearColor];
if (array_indexpath.count !=0)
{
for (int i=0; i<[array_indexpath count]; i++)
{
if ([array_indexpath objectAtIndex:i] == indexPath)
{
cell.backgroundColor=[UIColor greenColor];
}
}
}
return cell;
}
Hope it helps.. Happy Coding.. :)
I'm not using storyboard, everything is done by code..
and when I scroll the UICollectionView.. after it reusing correctly..some cells..
than it happen :
-the cell initWithFrame is being call
-new gray hair appear on my head.
I read other q/a and check maybe it's something with threads but all the reloadData is on the main thread.
any directions ?
I have no idea what's your code, so I'll propose how do I do it:
// somewhere in eg viewDidLoad
[self.collectionView setDelegate:self];
[self.collectionView setDataSource:self];
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:CellId];
And later the delegate:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = cell = [collectionView dequeueReusableCellWithReuseIdentifier:MyCellId forIndexPath:indexPath];
// do something with your cell, set title or anything
return cell;
}
There is another possibility. Your cell, as it's reusable, will have already saved previous properties. So if you did something like this:
if (iCanAddGrayHair) {
[cell.imageView setImage:[UIImage imageNamed:#"hair"]]
}
Then do notice, that new cell will still have this image set! You need to add:
else {
[cell.imageView setImage:nil];
}
To reset it from previous state. You can also override prepareForReuse: method of UICollectionViewCell class to reset the values (don't forget to call super).
I have implemented an UICollectionView image gallery. Each cell has some views and I would like to hide or show that views when I change the current cell, at least when the event starts. is there any method? or should I do something by delegate? I have paging enabled and custom cell and FlowLayout.
I have done everything almost like this tutorial
One way would be to keep the current selected cell index in a local variable in your viewController, and use that index to perform any actions when selecting another cell:
#property (nonatomic) NSIndexPath *selectedCellIndexPath;
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
if (![self.selectedCellIndexPath isEqual:indexPath]) {
UICollectionViewCell *lastSelectedCell = [collectionView cellForItemAtIndexPath:selectedIndexPath];
// Perform any change to lastSelectedCell before deselecting it
[collectionView deselectItemAtIndexPath:lastSelectedIndexPath animated:YES];
}
self.selectedCellIndexPath = indexPath;
UICollectionViewCell *selectedCell = [collectionView cellForItemAtIndexPath:indexPath];
// Change what you want in the newly selected cell;
}
I have a UICollectionView controller embedded inside a navigation controller. The collectionView lists projects and each cell is supposed to segue to a ProjectDetail screen.
I simply cannot get the segue to trigger. If I simply drop a button on the nav bar and hook up a segue to the detail, it works. But triggering from my CollectionView cell doesn't.
Here is what the storyboard looks like: http://cl.ly/RfcM I do have a segue hooked up from the CollectionViewCell to the ProjectDetailViewController
Here's the relevant code inside my ProjectDetailViewController:
#interface ProjectCollectionViewController () {
NSArray *feedPhotos;
Projects *projects;
}
#end
#implementation ProjectCollectionViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self.collectionView registerClass:[FeedViewCell class] forCellWithReuseIdentifier:#"cell"];
[self loadData];
}
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
NSLog(#"selected %d", indexPath.row);
Project *project = [projects getProject:indexPath.row];
NSLog(#"project = %#", project);
}
- (void)loadData {
[self.projectLoader loadFeed:self.username
onSuccess:^(Projects *loadedProjects) {
NSLog(#"view did load on success : projects %#", loadedProjects);
projects = loadedProjects;
[self.collectionView reloadData];
}
onFailure:^(NSError *error) {
[self handleConnectionError:error];
}];
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return projects.count;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
static NSString *identifier = #"cell";
FeedViewCell *cell = (FeedViewCell *) [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:1.0 alpha:1.0];
UIImageView *cellImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
Project *project = [projects getProject:indexPath.row];
NSString *imageUrl = [project coverPhotoUrl:200 forHeight:200];
NSLog(#"imageurl =>%#", imageUrl);
if (imageUrl) {
[cellImageView setImageWithURL:[NSURL URLWithString:imageUrl]];
}
[cell addSubview:cellImageView];
cell.imageView = cellImageView;
return cell;
}
I'm guessing the problem is somewhere in how I'm hooking up the Cells to the CollectionView.
Any help would be greatly appreciated!
You cannot create segues directly from cells in a storyboard because the collectionview is populated dynamically through the data source. You should use the collectionView:didSelectItemAtIndexPath: and perform the segue programatically using performSegueWithIdentifier:sender:. Something like this:
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
[self performSegueWithIdentifier:#"MySegueIdentifier" sender:self];
}
where MySegueIdentifier is the identifier of the segue defined in storyboard.
TLDR: FOR A STORYBOARD, do not call registerClass:forCellWithReuseIdentifier:. It overrides what the storyboard sets up for the cell (including how segues are handled):
How to set a UILabel in UICollectionViewCell
Brief setup
Used a storyboard
Created a new collection view controller using the Xcode template,
setting it as a subclass of UICollectionViewController.
Initially used the default UICollectionViewCell, adding a UILabel
programmatically.
The generated UICollectionViewController code registered the cell in viewDidLoad:
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:reuseIdentifier];
First Issue:
The prepareForSegue:sender: event was not firing, which brought me to this answer .
I implemented the UICollectionViewDelegate and collectionView:didSelectItemAtIndexPath: event, then called the segue programmatically.
This fixed my first issue.
Second Issue: I switched to a custom cell containing one label. After hooking everything up, the cell label was not displaying.
After some digging, I found a solution contained in the link at the top of my answer.
Third Issue and Solution: I removed the registerClass:forCellWithReuseIdentifier: line. When I ran my app, the label appeared correctly, but when I tapped a cell, it called the prepareForSegue:sender event twice. By removing the registerClass:forCellWithReuseIdentifier line, the cell was processing cell touches directly, without the need of the delegate method. This is how I expected the storyboard to work. I deleted the collectionView:didSelectItemAtIndexPath: event, which resolved the double-firing of prepareForSegue:sender:. If you are using a storyboard, do not register the cell class. It overwrites what storyboard sets up.
Have you made your CollectionView Cell's connection in Triggered Segues on selection?
You can also trigger a segue programatically using
[self performSegueWithIdentifier:#"segueIdentifier" sender:nil]
in
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
Equivalent Swift code for similar question.
override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
self.performSegueWithIdentifier(#"TargetSegway", sender: self)
}
Make sure, in case if your cell has other overlapping views, "User Interaction Enabled" is unchecked (you can find this option, under attribute inspector View/Interaction). Otherwise, your Tap Gesture is consumed by the overlapping view, didSelectItemAtIndexPath may not be called.
How do you disable selecting only a single cell in a UITableView? I have several, and I only want the last to be disabled.
To stop just some cells being selected use:
cell.userInteractionEnabled = NO;
As well as preventing selection, this also stops tableView:didSelectRowAtIndexPath: being called for the cells that have it set. It will also make voiceover treat it the same as a dimmed button (which may or may not be what you want).
Note that if you have interactive elements in the cell (ie. switches/buttons), you'll need to use cell.selectionStyle = UITableViewCellSelectionStyleNone; instead and then make sure to ignore taps on the cell in tableView:didSelectRowAtIndexPath:.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = ...
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
Throw this in your custom Table VC:
// cells lacking UITableViewCellAccessoryDisclosureIndicator will not be selectable
- (NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [self tableView:tableView cellForRowAtIndexPath:indexPath];
if (cell.accessoryType != UITableViewCellAccessoryDisclosureIndicator) {
return nil;
}
return indexPath;
}
// disabled cells will still have userinteraction enabled for their subviews
- (void)setEnabled:(BOOL)enabled forTableViewCell:(UITableViewCell *)tableViewCell
{
tableViewCell.accessoryType = (enabled) ? UITableViewCellAccessoryDisclosureIndicator : UITableViewCellAccessoryNone;
// if you dont want the blue selection on tap, comment out the following line
tableViewCell.selectionStyle = (enabled) ? UITableViewCellSelectionStyleBlue : UITableViewCellSelectionStyleNone;
}
Then to enable/disable selection for someTableViewCell, do this:
[self setEnabled:state forTableViewCell:someTableViewCell];
You're done and can ship.
-(NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
if ([self numberOfRowsInSection] == [indexPath row]) {
return nil;
} else {
return indexPath;
}
}
the last row of the table will not be selected
As I mentioned in another thread all the above methods are not solving the problem precisely. The correct way of disabling a cell is through the method
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
and in that method one has to use
[cell setSelectionStyle:UITableViewCellSelectionStyleNone];
which disables cell selection but still allows the user to interact with subviews of the cell such as a UISwitch.
The cleanest solution that I have found to this only makes use of the delegate method willDisplayCell.
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
if([indexPath row] == 0) //<-----ignores touches on first cell in the UITableView
{ //simply change this around to suit your needs
cell.userInteractionEnabled = NO;
cell.textLabel.enabled = NO;
cell.detailTextLabel.enabled = NO;
}
}
You don't have to take any further action in the delegate method didSelectRowAtIndexPath to ensure that the selection of this cell is ignored. All touches on this cell will be ignored and the text in the cell will be grayed out as well.
with iOS 6.
You can use the following delegate method and return NO in case you don't it to be selected and YES in case you want it to be selected.
- (BOOL)tableView:(UITableView *)tableView shouldHighlightRowAtIndexPath:(NSIndexPath *)indexPath
{
return indexPath.section == 0;
}
Try this in swift:
self.tableView.deselectRowAtIndexPath(indexPath, animated: true)
If anyone wondering how to achieve this in swift then here is my code. I am using Xcode 7 and tested using iPad Retina(iOS 9).
cell.selectionStyle = UITableViewCellSelectionStyle .None
cell.userInteractionEnabled = false
Try to place this two line code whether you want. In my case I have used this in this method for displaying cells.
override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath)
Remember this two line code will block any kind of selection or interaction to your cells but you can only use the first line individually if you want. That is...
cell.selectionStyle = UITableViewCellSelectionStyle .None
Only this line will block the selection to your cells.
However the second line will make the cell "Read-Only". That is..
cell.userInteractionEnabled = false
Thanks
Hope this helped.