Hello I am having trouble getting a custom object at the index path of the UICollectionView...
Below is my code.
I am getting the crash
[Player firstName:]: unrecognized selector sent to instance
Any suggestions?
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
BenchCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CollectionCell forIndexPath:indexPath];
[cell setFrame:CGRectMake(0, 4, 120, 50)];
Player*homeBenchPlayer = [[self homeBench]objectAtIndex:indexPath.row];
cell.playerName.text = homeBenchPlayer.firstName;
cell.playerPosition .text = homeBenchPlayer.position;
cell.playerPicture.image = [ UIImage imageWithData:homeBenchPlayer.picture];
return cell;
}
When I get this error unexpectedly I usually return to IB, select the object responsible for the crash, and investigate the Connections Inspector. Generally the problem seems to be an incorrect referencing outlet or sent event.
This could be caused by calling performSelector:#selector(dismissModal:) where the callee doesn't exist.
Related
I have a UICollectionView on iOS7 which crashes randomly when intense scrolling. I enabled zombies and found that it gives me an error saying:
*** -[NSIndexPath section]: message sent to deallocated instance 0x17dbc970
I believe this is due to an Apple error described here. Apparently, the app crashes when someone highlights a cell while scrolling fast, and then the OS tries to unhighlight it when it moves off screen, when it ceases to exist. The proposed solution is to disable the userInteractionEnabled property of the cell and then handle the selection using UIGestureRecogniser.
Has anyone else faced this same issue? Also, I tried unsetting the userInteractionEnabled property and using a gesture recogniser, but this doesn't seem to work. Any idea how I can fix this?
EDIT: Code added on request
-(UICollectionViewCell*) collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
NSString *CellIdentifier = #"Gallery_Cell";
GalleryCell *cell= (GalleryCell *)[self.flowCollection dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];
if (indexPath.row < self.collectionData.count) {
CellDetails *dets = [self.collectionData objectAtIndex:indexPath.row];
NSURL *mainImageURL = [NSURL URLWithString:dets.imageURL];
cell.image.contentMode = UIViewContentModeScaleAspectFill;
cell.image.clipsToBounds = YES;
if ([[[SDWebImageManager sharedManager] imageCache] imageFromDiskCacheForKey:[self cacheKeyForURL:mainImageURL]] == nil) {
[cell.image setImageWithURL:mainImageURL placeholderImage:nil];
}else{
[cell.image setImage:[[[SDWebImageManager sharedManager] imageCache] imageFromDiskCacheForKey:[self cacheKeyForURL:mainImageURL]]];
}
}
return cell;
}
EDIT: more code..
I defined the GalleryCell for reuse as follows:
[self.flowCollection registerNib:[UINib nibWithNibName:#"Thumbs_Cell" bundle:nil] forCellWithReuseIdentifier:#"Gallery_Cell"];
The GalleryCell class implementation is:
GalleryCell.h
#interface GalleryCell : UICollectionViewCell
#property (nonatomic, retain) IBOutlet UIImageView *image;
#end
GalleryCell.m
#implementation GalleryCell
#synthesize image;
-(void) setHighlighted:(BOOL)highlighted {
[super setHighlighted:highlighted];
[self setNeedsDisplay];
}
-(void)prepareForReuse {
[super prepareForReuse];
[self.image cancelCurrentImageLoad]; // SDWebImage method to cancel ongoing image load
}
OK. I seem to have solved it. In case anyone faces this problem, here is the fix:
I implemented the following method in my UICollectionViewDelegate:
-(BOOL) collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath{
return NO;
}
This prevents any cell from highlighting, and hence, avoids the crash when the system tries to unhighlight it when it goes off-screen. But, when you do this it also stops calling the didSelectItemAtIndexPath method. So I had to use a UITapGestureRecogniser method to implement cell selection instead.
Hope this helps.
I would suggest returning the following:
- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath{
return !collectionView.dragging && !collectionView.tracking;
}
Okay, so i am building a basic UICollectoion view app in Xcode, going off of a tutorial on the Ray Wenderlich website, when I get to the point of running it, it searches for photos, and then i get an error with this line of code...
- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [cv dequeueReusableCellWithReuseIdentifier:#"FlickrCell " forIndexPath:indexPath]; //< error on this line
cell.backgroundColor = [UIColor whiteColor];
return cell;
}
What will fix this and allow the app to continue running?
Notice the trailing space in the identifier string.
"FlickrCell "
..........^
It should be "FlickerCell".
I have an iPad app, using Storyboards, Tab Bar and XCode 4.5. One of my scenes has a UITableView in the upper left quadrant, with labels and UITextBoxes in the right upper quadrant.
When I click on the second tab, I am taken to the scene described above. This is the code:
- (void)viewDidLoad {
[super viewDidLoad];
[self.collectionView registerClass:[Cell class] forCellWithReuseIdentifier:#"MY_CELL"];
}
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 4;
}
- (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section {
return 4;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath; {
Cell *cell = [cv dequeueReusableCellWithReuseIdentifier:#"MY_CELL" forIndexPath:indexPath];
cell.label.text = [NSString stringWithFormat:#"%d",indexPath.item];
return cell;
}
This is the interface definition:
#interface ClientViewController : UIViewController <UICollectionViewDelegate, UICollectionViewDataSource> {
}
This is the error:
* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIView
collectionView:numberOfItemsInSection:]: unrecognized selector sent to
instance 0x7d925b0'
As you see, I used the same code for numberOfSectionsInCollectionView. I have researched SO and Google and found nothing that applies.
What am I doing wrong?
There are two delegates to set. One is the delegate, and one is the dataSource. Generally, both should be set to point to your view controller (ie, self in most circumstances).
I am trying to use UICollectionViewCell, since all I want to display is an image. I can add the image to the cell using UIColor colorWithImage: on the UICollectionViewCell's contentView property.
In my loadView method, I am registering the cell as follows:
[self.collectionView registerClass:[ImageCell class] forCellWithReuseIdentifier:#"MyCell"];
Below is my cellForItemAtIndexPath method:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"MyCell" forIndexPath:indexPath];
// cell customization
return cell;
}
When I run it, as soon as it hits the dequeue line, it crashes with the following error:
*** Assertion failure in -[UICollectionView _dequeueReusableViewOfKind:withIdentifier:forIndexPath:]
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'could not dequeue a view of kind: UICollectionElementKindCell with identifier MyCell - must register a nib or a class for the identifier or connect a prototype cell in a storyboard'
I tired setting up a custom cell, and used it as the class and I got the same error. My custom cell subclassed UICollectionViewCell and had nothing implemented, except for the default initWithFrame. That is because I wanted to just change the background colour of the view. I am not sure what the problem is but could someone please take a look at my code and help me? I've been trying to figure this out for quite a while with absolutely no luck at all.
If you just want to display an image, you don't need to do any subclassing, you can set the cell's backgroundColor with colorWithPatternImage:. Register the class like this:
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:#"Cell"];
Then use it like so:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"Cell" forIndexPath:indexPath];
cell.backgroundColor = [UIColor colorWithPatternImage:[self.results objectAtIndex:indexPath.row]];
return cell;
}
In this example, results is an array of UIImages.
If you are using xib in applivation then add following in your viewdidLoad method
[self.myCollectionView registerNib:[UINib nibWithNibName:#"CollectionViewCell" bundle:nil] forCellWithReuseIdentifier:#"CellIdentifier"];
otherwise If you using storyboard add following
[self.myCollectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:#"CellIdentifier"];
Finally add this (If not)
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"CellIdentifier" forIndexPath:indexPath];
return cell;
}
Hope above will help.
Try setting a breakpoint on
[self.collectionView registerClass:[ImageCell class] forCellWithReuseIdentifier:#"MyCell"];
I would guess your loadView (did you mean viewDidLoad?) method is not being called, so the class is never registered with the collectionView.
if your collection view is connected on storyboard and the delegate and datasource is set there, and you provide the necessary methods for the datasource and delegate, then adding the register call makes the
- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath
return a UICollectionView instead of your own subclass of it. So do either but not both.
set your cell identifier name as in code
I think many of us has faced this problem on UITableView delegate method - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath which gets called twice.
In my application I transforming the tableView. The code is:
CGAffineTransform transform = CGAffineTransformMakeRotation(-M_PI/2);
theTableView.transform = transform;
theTableView.rowHeight = self.bounds.size.width;
theTableView.frame = self.bounds;
Now inside the delegate method I am doing a couple of things:
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath
{
modelRef.currentCellAtIndexPathRow = indexPath.row;
static NSString *CellIdentifier = #"Cell";
CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
cell = [[[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier frame:self.bounds] autorelease];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
modelRef.currentPageIndex = (indexPath.row + 1);
[cell showPage];
NSLog(#" visible cell %i ",[[tableView visibleCells] count]);
return cell;
}
At a time 1 cell is visible, but first time when the application launches. The log shows visible cells 0.
Many a times this particular delegate method gets called twice abruptly.
How can I solve this?
I think an immediate fix is just to set a flag which changes the first time it is hit, so then you ignore the second call. It's probably not the perfect solution, and I can't tell you why it gets hit twice - but this will work. (I have experienced exactly the same behavior when I implemented an Apple delegate from the UIWebView class)
EDIT:
Create a BOOL member in the class header, then in the init set the value to be YES. So if the BOOL is called mbIsFirstCall for example, in your delegate method, do the following:
if (mbIsFirstCall)
{
// do your processing, then the line below
mbIsFirstCall = NO;
}
else
{
// you don't need this else, but just for clarity it is here.
// you should only end up inside here when this method is hit the second time, so we ignore it.
}