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".
Related
With XCode 6 and iOS 8 I encountered the problem that UICollectionViewCells does not autolayout / autoresize the subviews at first appearance. Once they have been shown and the cell is reused everything is fine.
I put
[cell layoutIfNeeded];
after the dequeueReusableCellWithReuseIdentifier-Statement and everything was fine again.
I had the same issue. I tried to put [cell layoutIfNeeded];, but when I refresh the tableview, not all the cells are refreshed.
With the code [cell layoutSubviews]; just before returning the cell, all cells are updated every time. Here is the complete piece of code
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
MyCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:kCellID forIndexPath:indexPath];
...
[cell layoutSubviews];
return cell;
}
I've a collection view with custom cell class.
In each cell I've a player with a specific sound.
When made an Button and link to my code with an IBOutlet, it's doesn't fire even with the fact I have userInteractionEnabled = YES in all my views.
So I decided to play the sound in the collection view controller.
In my cell the player has a property
#property (strong, nonatomic) AVAudioPlayer *voicePlayer;
Then in the collection I have:
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
LHFriendVoiceCollectionViewCell *cell = [self.collectionView dequeueReusableCellWithReuseIdentifier:#"LHFriendVoiceCollectionViewCell" forIndexPath:indexPath];
LHFriendVoiceObject *currentFriendVoice = [[LHFriendVoiceObject alloc] initWithNSDictionnary:[self.friendsArray objectAtIndex:indexPath.row]];
[cell hydrateWithFriendVoiceObject:currentFriendVoice];
[cell.voicePlayer prepareToPlay];
//[self.voicesArray addObject:cell.voicePlayer]; tried to stock them in array but doesn't work
return cell;
}
If I play the sound in this method it's work, but I want the sound to be played when I select the cell.
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath: (NSIndexPath *)indexPath {
LHFriendVoiceCollectionViewCell *cell =
[self.collectionView dequeueReusableCellWithReuseIdentifier:#"LHFriendVoiceCollectionViewCell" forIndexPath:indexPath];
[cell.voicePlayer play];
}
Here the sound doesn't play because voicePlayer is nil.
How I can keep my players ?
This code is the problem:
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath: (NSIndexPath *)indexPath {
LHFriendVoiceCollectionViewCell *cell =
[self.collectionView dequeueReusableCellWithReuseIdentifier:#"LHFriendVoiceCollectionViewCell" forIndexPath:indexPath];
[cell.voicePlayer play];
}
That first line is wrong. You are calling dequeue. Big mistake! It makes a completely new cell. Do not make a new cell like that! Obviously that new cell will not have any AVAudioPlayer in it.
You already have a cell; it just got selected. Use the indexPath and cellForItemAtIndexPath: to learn out which cell got selected. That is the one you want to talk to.
PS You really should figure out why the button approach didn't work, but it's no big deal at this point.
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;
}
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.
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