I'm trying to implement a custom UICollectionView that shows all elements from the asset library. While displaying the items is not that big of a deal, I run into a weird bug which I think has to do something with the layout I'm using.
Let's start with some screenshots to indicate what's going on. I'll just post the links to these images to be easy on your scroll wheels :-)
1. Initial
https://dl.dropboxusercontent.com/u/607872/stackoverflow/01-uicollectionview-start.png
Everything ok.
2. Scrolled down
https://dl.dropboxusercontent.com/u/607872/stackoverflow/02-uicollectionview-scrolleddown.png
The images from the first row (which isn't visible anymore) repeat behind the images in the last row. The first one is invisible because it is entirely overlapped.
3. Scrolled up again
https://dl.dropboxusercontent.com/u/607872/stackoverflow/03-uicollectionview-scrollup.png
The first image (in the background) is from the same row, but should be the third. The 2nd and 3rd image are from the last row.
Here's some code. I hope I didn't miss any relevant stuff - if so, please let me know.
MultiImagePickerController.m (:UICollectionViewController, protocols: UICollectionViewDataSource, UICollectionViewDelegateFlowLayout)
- (void)loadView {
[...] // layout stuff
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
[layout setScrollDirection:UICollectionViewScrollDirectionVertical];
_collectionView = [[UICollectionView alloc] initWithFrame:collectionRect collectionViewLayout:layout];
[_collectionView setDataSource:self];
[_collectionView setDelegate:self];
[_collectionView registerClass:[MultiImagePickerCell class] forCellWithReuseIdentifier:#"MultiImagePickerCellIdentifier"];
[_collectionView setBackgroundColor:[UIColor whiteColor]];
[self.view addSubview:_collectionView];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
MultiImagePickerCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"MultiImagePickerCellIdentifier" forIndexPath:indexPath];
if ( !cell ) {
CGSize sizeCell = [MultiImagePickerCell defaultSize];
cell = [[MultiImagePickerCell alloc] initWithFrame:CGRectMake( 0, 0, sizeCell.width, sizeCell.height )];
}
NSString *groupname = [self getKeyFromMutableDictionary:assetList forIndex:indexPath.section];
[cell addImageUsingAsset:[[assetList objectForKey:groupname] objectAtIndex:indexPath.row]];
return cell;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
CGSize sizeCell = [MultiImagePickerCell defaultSize];
return CGSizeMake( sizeCell.width + 10.0, sizeCell.height + 10.0 );
}
MultiImagePickerCell - (void)addImageUsingAsset:(ALAsset *)asset;
This method adds a UIImageView and a UIImage to the cell to show the asset. Nothing special, in my opinion. When I set breakpoints in cellForItemAtIndexPath, I can see that the correct asset is being read from the assetList and the views are calculated correctly. The drawRect method of the cell is NOT implemented.
I think I experienced the same problem a few years back when I tried to programmatically create a UITableViewController, but I can't remember how I solved it.
Any suggestions?
Got it - I had to remove the subviews from my cells.
Related
So I switched from a UITableView to a UICollectionView. The cells are all loading just fine and look beautiful, but now I can no longer select any of them. The taps are recognized in the logs, but it doesn't take me to the view that it's supposed to take me to anymore.
The only things that changed really are the ones the ones you see commented out in the "cellForItem" section. Everything else is identical to how it was when it was working in the TableView. It's just supposed to take me to the ViewController specified when you tap. Instead the tap is recorded, but it does nothing. Any help would be appreciated.
Also I tried getting rid of the [collectionView deselectItemAtIndexPath:indexPath animated:YES];
...but it didn't make any difference.
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
PlaceCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
// Configure the cell
//UINib * placeCell = [UINib nibWithNibName:#"Shops" bundle:nil];
// NSArray *topLevelItems = [placeCell instantiateWithOwner:self options:nil];
// cell = [topLevelItems objectAtIndex:0];
Place *p = [_entries objectAtIndex:indexPath.row];
cell.placeName.text = p.PName;
NSLog(#"p:%#",p.PName);
cell.placeName.textColor = [UIColor colorWithRed:3/255.0f green:6/255.0f blue:4/255.0f alpha:1.0f];
NSString *pIcon;
pIcon = typeName;
//NSLog(pIcon);
cell.placeImg.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:p.PImage]]];
NSLog(#"i:%#",p.PImage);
return cell;
}
-(void) collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
NSLog(#"Tap Recognized");
[collectionView deselectItemAtIndexPath:indexPath animated:YES];
Place *p = [_entries objectAtIndex:indexPath.row];
DetailPlaceViewController * pvc = [[DetailPlaceViewController alloc] init];
[pvc setPlace:p];
[self.navigationController pushViewController:pvc animated:YES];
}
Well this one was fun...
For some odd reason my navigation controller isn't working... so of course using the navigation controller to load a view wasn't going to work. Simple enough solution... load the view without the navigation controller. I was just going to delete this question, but maybe somebody might be in a similar situation one day:
[self presentViewController:pvc animated:YES completion:nil];
EDIT: I should specify that this only happens when I attempt to use the UICollectionViewFlowLayout, not when I try to use a custom view. But either way nothing ever shows up on the CollectionView though it was working just fine before I converted from a TableView.)
So I've been trying to convert a UITableView that I had into a UICollectionView. So far so good. But when I try to run the app it gives me the error:
'the collection view's data source did not return a valid cell from -collectionView:cellForItemAtIndexPath: for index path {length = 2, path = 0 - 0}'
I checked all the similar questions and answers here... so in my viewDidLoad I have (tableView is actually a UICollectionView):
UINib * placeCell = [UINib nibWithNibName:#"Shops" bundle:nil];
[self.tableView registerNib:placeCell
forCellWithReuseIdentifier:CellIdentifier];
#pragma mark - UICollectionViewDataSource
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UICollectionView *)tableView numberOfItemsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [_entries count];
//return 5;
}
- (void)tableView:(UICollectionView *)tableView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.item == [_entries count]-1 && page > 1) {
NSLog(#"load more");
//add footer view loading
if (c_page == page) {
// _tableView.tableFooterView = nil;
}
else
{
c_page++;
[self loadPlace:c_page];
}
}
}
- (UICollectionViewCell *)tableView:(UICollectionView *)tableView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
PlaceCell *cell = (PlaceCell *)[tableView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];
UINib * placeCell = [UINib nibWithNibName:#"Shops" bundle:nil];
//cell = [cellLoader instantiateWithOwner:self options:nil];
NSArray *topLevelItems = [placeCell instantiateWithOwner:self options:nil];
cell = [topLevelItems objectAtIndex:0];
Place *p = [_entries objectAtIndex:indexPath.row];
cell.placeName.text = p.PName;
NSLog (#"p:%#", p.PName")
cell.placeImg.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:p.PImage]]];
return cell;
}
I went into the xib of the UICollectionViewCell (PlaceCell) and made sure that "Cell" was the reuseidentifier. And I made sure that the datasource and delegate were connected to file's owner in the collectionView.
I also noticed that when I use a custom layout instead of the flow layout (like this one: https://github.com/ShadoFlameX/PhotoCollectionView/blob/master/CollectionViewTutorial/BHPhotoAlbumLayout.m ) it doesn't give me that error... but my collectionview still isn't populated.
So I'm wondering if there's some sort of log I can run or something I can do to figure out what's going wrong. Because I've tried all the solutions I've seen and it hasn't gotten me anywhere.
When you make a cell in a xib file you should register the xib, not the class. Also, when you register either the class or xib (or make the cell in the storyboard), you don't need an if (cell==nil) clause because your cell will never be nil when you dequeue it with dequeueReusableCellWithReuseIdentifier:forIndexPath:. You should delete that clause.
So the problem is: "Switched from UITableView to UICollectionView and no valid cell is being returned." It is really a two part answer. The crux of which is every instance of UITableView...
_tableView = [[UITableView alloc] initWithFrame:CGRectMake(0, 50, self.view.bounds.size.width, self.view.bounds.size.height-50)];
...you want to turn into "CollectionView"
_collectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 50, self.view.bounds.size.width, self.view.bounds.size.height-50)];
Everything that's a "row":
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
...you'll want to turn into an "item."
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
Ultimately I had to delete the following section entirely:
UINib * placeCell = [UINib nibWithNibName:#"Shops" bundle:nil];
//cell = [cellLoader instantiateWithOwner:self options:nil];
NSArray *topLevelItems = [placeCell instantiateWithOwner:self options:nil];
cell = [topLevelItems objectAtIndex:0];
My best guess is that the Nib was being loaded twice and that Xcode was complaining that the data wasn't being loaded by the original. So getting rid of that second entry got my cells loaded and populated with data. Hope this helps someone.
I am currently working on a UICollectionView with a lot of images. However, it sometimes crashes in this view with memory warning. I am using AFNetworking and UIImageView+AFNetworking category to set image through setImageWithURL: method. One issue can be caching. I am not sure if AFNetworking deals with image caching. Anyway, is there a way to optimize this code in terms of memory management? Or if I am to implement didReceiveMemoryWarning method in this view controller, what can be put in this method? I attach the code for cellForItemAtIndexPath for this collection view.
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"RecipeCell" forIndexPath:indexPath];
// setting the image view for the cell using AFNetworking. Does this do caching automatically?
UIImageView *recipeImageView = (UIImageView *)[cell viewWithTag:6];
if (PRODUCTION) {
[recipeImageView setImageWithURL:[[self.recipes objectAtIndex:indexPath.row] objectForKey:#"recipe_image"] placeholderImage:[UIImage imageNamed:#"default_recipe_picture.png"]];
} else {
[recipeImageView setImageWithURL:[NSString stringWithFormat:#"http://localhost:5000/%#", [[self.recipes objectAtIndex:indexPath.row] objectForKey:#"recipe_image"]] placeholderImage:[UIImage imageNamed:#"default_recipe_picture.png"]];
}
// configure the back of the cell. fill all the info.
UITextView *recipeNameView = (UITextView *)[cell viewWithTag:8];
recipeNameView.text = [NSString stringWithFormat:#"%#", [[self.recipes objectAtIndex:indexPath.row] objectForKey:#"recipe_name"]];
UILabel *recipeNameLabel = (UILabel *)[cell viewWithTag:2];
recipeNameLabel.text = [NSString stringWithFormat:#"%#", [[self.recipes objectAtIndex:indexPath.row] objectForKey:#"recipe_name"]];
NSDictionary *user = [[self.recipes objectAtIndex:indexPath.row] objectForKey:#"user"];
UIButton *chefNameButton = (UIButton *)[cell viewWithTag:3];
[chefNameButton setTitle:[NSString stringWithFormat:#"%# %#", [user objectForKey:#"first_name"], [user objectForKey:#"last_name"]] forState:UIControlStateNormal];
NSMutableArray *missingIngredientsStringArray = [[NSMutableArray alloc] init];
NSArray *missingIngredients = [[self.recipes objectAtIndex:indexPath.row] objectForKey:#"missing_ingredients"];
for (NSDictionary *missingIngredient in missingIngredients) {
[missingIngredientsStringArray addObject:[missingIngredient objectForKey:#"name"]];
}
NSString *missingIngredientsString = [missingIngredientsStringArray componentsJoinedByString:#","];
UITextView *missingIngredientsView = (UITextView *)[cell viewWithTag:4];
missingIngredientsView.text = [NSString stringWithFormat:#"%u Missing Ingredients: %#", missingIngredients.count, missingIngredientsString];
// configure the front of the cell. chef name button and missing ingredients and likes on front view
UIButton *frontNameButton = (UIButton *)[cell viewWithTag:11];
[frontNameButton setTitle:[NSString stringWithFormat:#"%# %#", [user objectForKey:#"first_name"], [user objectForKey:#"last_name"]] forState:UIControlStateNormal];
[frontNameButton sizeToFit];
frontNameButton.frame = CGRectMake(160 - [frontNameButton.titleLabel.text sizeWithFont:[UIFont boldSystemFontOfSize:13]].width - 7, frontNameButton.frame.origin.y, frontNameButton.frame.size.width, frontNameButton.frame.size.height);
UILabel *likesLabel = (UILabel *)[cell viewWithTag:9];
likesLabel.text = [NSString stringWithFormat:#"%# likes", [[self.recipes objectAtIndex:indexPath.row] objectForKey:#"likes"]];
UIButton *missingIngredientsButton = (UIButton *)[cell viewWithTag:12];
[missingIngredientsButton setBackgroundImage:[UIImage imageNamed:#"badge_green.png"] forState:UIControlStateSelected];
if (missingIngredients.count == 0) {
missingIngredientsButton.selected = YES;
[missingIngredientsButton setTitle:#"" forState:UIControlStateNormal];
} else {
missingIngredientsButton.selected = NO;
[missingIngredientsButton setTitle:[NSString stringWithFormat:#"%u", missingIngredients.count] forState:UIControlStateNormal];
}
// make back view invisible.
UIView *backView = [cell viewWithTag:1];
UIView *frontView = [cell viewWithTag:5];
frontView.alpha = 1.0;
backView.alpha = 0;
// adding flip gesture recognizers
UIView *flipView1 = [cell viewWithTag:12];
UIView *flipView2 = [cell viewWithTag:1];
UITapGestureRecognizer *flipGestureRecognizer1 = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(flipCell:)];
UITapGestureRecognizer *flipGestureRecognizer2 = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(flipCell:)];
[flipView1 addGestureRecognizer:flipGestureRecognizer1];
[flipView2 addGestureRecognizer:flipGestureRecognizer2];
return cell;
}
[Edit] I attach a screenshot of my Instruments run.
You can see that memory allocation increases as I just push segue and press back button repeatedly. Things that just keep increasing are CFData, CALayer, CABackingStore, UITableView. I doubt these are things that are created after segue, and they are not being released... Please help!
You're probably going to want some sort of image caching strategy to avoid re-downloading images. And UIImageView+AFNetworking category does cache images for you. But you may also have the responses being cached in the in-memory URL cache, which in this case is somewhat redundant.
So you might consider reducing or turning off the in-memory URL cache. I had the issue you're describing and the following reduced my memory issues quite a bit:
NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:0 diskCapacity:0 diskPath:nil];
[NSURLCache setSharedURLCache:sharedCache];
AFNetworking automatically stores images in an NSCache collection, which automatically removes some or all of the images from memory on a low memory warning. AFNetworking is probably not your issue.
In fact, I don't think displaying images is your issue unless you're downloading lots of very large images and displaying them simultaneously. (If this is the case, you should try optimizing your images for display on the device so they don't need to be resized.)
One issue I see is that you are adding a gesture recognizer to the cell every time it comes into the view, but cells are reused, so when a cell comes in again you are adding unnecessary gesture recognizers to it. You could resolve this by subclassing UITableViewCell and assigning the gesture recognizers as properties. You could also resolve this by checking flipView1 and flipView2 to see if they have gesture recognizers attached before adding them. (I'm not sure if this is enough to cause a memory warning though.)
I'd recommend going to Build -> Profile and selecting the Allocations instrument. On the left, select Objective C only, and hide system calls. Then, scroll through your collection view and look at the instrument to see what's taking up all the memory.
UPDATE
Here's a screenshot of the Allocations tool:
I am new to OS X and have started dealing with NSCollectionView. What I am trying to do is to take show NSCollectionView with array of imageView an labels. And on the selection of the image I want to open a new viewController class. I am able to show array of images and labels in collection view but I am completely lost on how to go to new view with the selection made in NSCollectionView and how to show the image selected to the new viewController class.
I am having an NSTabView and in that I am having customView in which I am showing CollectionView. And in awakeFromNib I am doing this to populate my collectionView
-(void)awakeFromNib
{
arrItems = [[NSMutableArray alloc]init];
NSMutableArray *imageArray=[[NSMutableArray alloc]initWithObjects:#"Baby-Girl-Wallpaper-2012-7.jpg",#"Cute-Little-Baby-Girl.jpg",#"Joker_HD_Wallpaper_by_RiddleMeThisJoker.jpg",#"The-Dark-Angel-Wallpaper-HD.jpg",#"hd-wallpapers-1080p_hdwallpapersarena_dot_com.jpg",#"lion_hd_wallpaper.jpg",#"Ganesh_painting.jpg",#"krishna-wallpaper.jpg",#"LeoN_userpic_79630_fire_lion_by_alex_barrera.jpg",#"273483.png",#"japan_digital_nature-wide.jpg", nil];
NSMutableArray *imageName = [[NSMutableArray alloc]initWithObjects:#"Baby-Girl",#"Cute-Little",#"Joker",#"The-Dark",#"hd-wallpapers", #"lion", #"Ganesh", #"krishna", #"LeoN_userpic",#"273483.png",#"japan_digital", nil];
for(int i = 0; i<[imageArray count]; i++)
{
STImageCollectionModal * img1 = [[STImageCollectionModal alloc] init];
img1.image = [NSImage imageNamed:[imageArray objectAtIndex:i]];
img1.imageName = [NSString stringWithFormat:#"%#",[imageName objectAtIndex:i]];
[arrItems addObject:img1];
}
[collectionView setContent:arrItems];
}
Later I created a new class named "STCollectionView" subclass of NSCollectionView and assigned the collectionView class to "STCollectionView" and with the help of setSelectionIndexes method I tried getting the index of the selected item by this
- (void)setSelectionIndexes:(NSIndexSet *)indexes
NSLog(#"%ld",[indexes firstIndex]);
But this method is getting called twice and whenever i put "super setSelectionIndexes" it gives me garbage value.
I am searching it all over but unable to find any kind of solution. Please help..
Thank you in advance.
Your question is confusing me.What i am thinking you can do this task simply by adding UICollectionView and in UICollectionView add custom UICollectionViewCell.In custom UICollectionViewCell add UIImageView and UILabel.
in the method
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
static NSString *identifier = #"ReuseID";
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.imageView.image = [UIImage imagewithNmaed:#"your Image name"];
cell.label.text = #"image Named";
return cell;
}
and in storyBoard hold CLT+drag to your UIViewController.In the method prepareForSgue Method pass data to your Next viewController.
Greetings all,
I am a noob and I have been trying to work through this for a few days.
I am adding images to a view via UItouch. The view contains a background on top of which the new images are add. How do I clear the images I am adding from the subview, without getting rid of the UIImage that is the background. Any assistance is greatly appreciated. Thanks in Advance.
here is the code:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *) event {
NSUInteger numTaps = [[touches anyObject] tapCount];
if (numTaps==2) {
imageCounter.text =#"two taps registered";
//__ remove images
UIView* subview;
while ((subview = [[self.view subviews] lastObject]) != nil)
[subview removeFromSuperview];
return;
}else {
UITouch *touch = [touches anyObject];
CGPoint touchPoint = [touch locationInView:self.view];
CGRect myImageRect = CGRectMake((touchPoint.x -40), (touchPoint.y -45), 80.0f, 90.0f);
UIImageView *myImage = [[UIImageView alloc] initWithFrame:myImageRect];
[myImage setImage:[UIImage imageNamed:#"pg6_dog_button.png"]];
myImage.opaque = YES; // explicitly opaque for performance
[self.view addSubview:myImage];
[myImage release];
[imagesArray addObject:myImage];
NSNumber *arrayCount =[self.view.subviews count];
viewArrayCount.text =[NSString stringWithFormat:#"%d",arrayCount];
imageCount=imageCount++;
imageCounter.text =[NSString stringWithFormat:#"%d",imageCount];
}
}
What you need is a way of distinguishing the added UIImageView objects from the background UIImageView. There are two ways I can think of to do this.
Approach 1: Assign added UIImageView objects a special tag value
Each UIView object has a tag property which is simply an integer value that can be used to identify that view. You could set the tag value of each added view to 7 like this:
myImage.tag = 7;
Then, to remove the added views, you could step through all of the subviews and only remove the ones with a tag value of 7:
for (UIView *subview in [self.view subviews]) {
if (subview.tag == 7) {
[subview removeFromSuperview];
}
}
Approach 2: Remember the background view
Another approach is to keep a reference to the background view so you can distinguish it from the added views. Make an IBOutlet for the background UIImageView and assign it the usual way in Interface Builder. Then, before removing a subview, just make sure it's not the background view.
for (UIView *subview in [self.view subviews]) {
if (subview != self.backgroundImageView) {
[subview removeFromSuperview];
}
}
A more swiftly code for approach #1 in only one functional line of code :
self.view.subviews.filter({$0.tag == 7}).forEach({$0.removeFromSuperview()})