I need some help with a uicollectionview that I've been trying to implement in Objective-C/xcode: I am unable to have the cells appear/populate the collectionview (CV).
Currently I am using the interface builder, and a custom class for cells.
The CV is to be a wide strip that is a single row of square image cells, that can be scrolled/swept through horizontally.
My attempts at implementation result in the wide strip but it never populates with cells.
I have explored other stackoverflow threads similar to this issue, where they discuss the subclassing of cell but I was unable to make it work. Have also tried programmatic implementation and had the same issue. Would really appreciate any insight as I have been stuck at this point for days. Below the code I am using, are screenshots of interface builder showing different settings... some I know are useful to include and I apologize if I have shared anything useless.
from ViewController.h
#interface ViewController : UIViewController <UICollectionViewDelegate,UICollectionViewDataSource>
#property (weak, nonatomic) NSMutableArray *medCollectionCells;
from ViewController.m
#import "CoolCell.h"
#property (weak, nonatomic) IBOutlet UICollectionView *medCollection;
- (void)viewDidLoad
{
_medCollectionCells = [NSMutableArray arrayWithObjects:#"1st cell",#"2nd cell",#"3rd cell",#"4th cell",#"5th cell",#"6th cell",#"7th cell",#"8th cell",#"5th cell", nil];
self.medCollection.delegate = self;
self.medCollection.dataSource = self;
}
// collection view delegate methods
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return [_medCollectionCells count];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
CoolCell *cell = (CoolCell *)[_medCollection dequeueReusableCellWithReuseIdentifier:#"MyCustomCell" forIndexPath:indexPath];
cell.backgroundColor = [UIColor blackColor];
return cell;
}
CoolCell.h:
#import <UIKit/UIKit.h>
#interface CoolCell : UICollectionViewCell
#property (weak, nonatomic) IBOutlet UILabel *customLabel;
#property (weak, nonatomic) IBOutlet UIImageView *customImage;
#end
CoolCell.m:
#import "CoolCell.h"
#implementation CoolCell
#end
Screen Shots
Storyboard layout
Collection View Settings 1
Collection View Settings 2
Cell Settings 1
Cell Settings 2
Interface Builder Outlets
Grateful for any assistance/insight. Thank you.
Seems like the delegate and dataSource properties are connected to a View object in Interface Builder. Maybe remove that since you are setting those properties in code.
Related
I have identical code in multiple view controllers and can't figure out why the Xcode compiler won't recognize a custom Cell.
In storyboards, the VCs have a view controller containing a tableView with 1 dynamic cell.
This cell is set in identity inspector to a custom cell.
In the file for the VC, in CellForRowAtIndexPath I have the following code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = #"Cell";
myCustomCell* cell = [self.tableView dequeueReusableCellWithIdentifier:#"Cell"];
The only difference between the custom cells is some were created in older versions of Xcode and don't have the NS_ASSUME_NONNULL_BEGIN and END lines:
#import <UIKit/UIKit.h>
#interface contactCell : UITableViewCell
#property (weak, nonatomic) IBOutlet UIImageView *imageView;
#property (weak, nonatomic) IBOutlet UILabel *someLabel;
#end
vs.
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
#interface ideaCell : UITableViewCell
#property (weak, nonatomic) IBOutlet UIImageView *imageView;
#property (weak, nonatomic) IBOutlet UILabel *someLabel;
#end
NS_ASSUME_NONNULL_END
However, if I set a breakpoint after the working one it shows:
However, if I set a breakpoint after the non-working on it shows a generic uitableviewcell.
Why isn't it recognizing the custom Cell?
I have tried deleting the cell and recreating it as well as cleaning the build folder.
Thanks for any suggestion.
Edit:
Here is storyboard:
I've succesfully created custom UICollectionViewCell that has 3 labels.
Now I want to subclass it, add dateToDisplay property and in setDateToDisplay change labels's strings (with custom date formatters).
Creation and usage of parentCell:
ParentCellIdentifier.h
static NSString *ParentCellIdentifier = #"ParentCellIdentifier";
#interface ParentCell : UICollectionViewCell
#property (strong, nonatomic) IBOutlet UILabel *firstLabel;
#property (strong, nonatomic) IBOutlet UILabel *secondLabel;
#property (strong, nonatomic) IBOutlet UILabel *thirdLabel;
-(void)setupDefaults;
#end
In parentCell.xib:
Class set to ParentCell and Identifier set to ParentCellIdentifier
In ViewController I have UICollectionView:
-(void)setupCollectionView {
[_daysCollectionView registerNib:[UINib nibWithNibName:#"ParentCell" bundle:nil] forCellWithReuseIdentifier:ParentCellIdentifier];
_daysCollectionView.delegate = self;
_daysCollectionView.dataSource = self;
_daysCollectionView.backgroundColor = [UIColor clearColor];
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
ParentCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:ParentCellIdentifier forIndexPath:indexPath];
cell.firstLabel.text = #"first";
cell.secondLabel.text = #"second";
}
The setup above worked like a charm.
No I want to add ChildCell, using same xib as previously:
#interface ChildCell : ParentCell
#property (nonatomic, strong) NSDate* dateToDislpay;//labels of parentCell updated using dateformatters on setDateToDisplay:
#end
-(void)setupCollectionView left the same, registering ParentCell.xib for ParentCellIdentifier
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
ChildCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:ParentCellIdentifier forIndexPath:indexPath];
NSDate* date = [_dates objectAtIndex:indexPath.row];
cell.dateToDislpay = date; //here goes the error
When trying to set property of child cell, it crashes. It's correct, because in ParentCell.xib class of the cell is ParentCell.
After changing the class in xib, it works, but I want to stick with my parent class in xib, since I will use the same xib, but with different formatters only.
How can I do it?
EDIT1:
crash received:
-[ParentCell setDateToDislpay:]: unrecognized selector sent to instance
You need to go into the xib file and change the class type to ChildCell and that should fix your crash.
To subclass see here: https://stackoverflow.com/a/5056886/848719
You'll have to override initWithFrame: and awakeFromNib.
You got crash because you have register [UINib nibWithNibName:#"ParentCell" bundle:nil] Parent Cell and in cell for item you are create object of ChildCell , but it is parent cell not child cell
and parent cell does not have dateToDislpay property .
you can check same with print class
you are doing inheritance wrong way, you should read some tutorial or read some demos
I am having a problem with my UITableView in iOS7. Initially, the data loads in just fine, and I get output in my console that proves that the cells are speaking to the data source correctly, but as soon as I tap anywhere on the table, the cells disappear and the table goes blank. The height of the cells in the empty UITableView seem to be honoring the height my custom prototype cell (410px), but all the data in the cells vanish, and the empty table view acts like it only has one cell in it (like its default state before it gets hooked up to the delegate).
I am using Storyboards for this app.
To get a little context, this app is similar to the iphone Instagram app, and I am using this application as way to learn iOS 7 development. I have been banging my head up against a wall trying to solve this issue, and I can't find any online resources that can help me solve this, so I wanted to ask all the smart peeps on Stack Overflow.
I have prepared a graphic that helps you see the problem
higher resolution version here
Here is my TableViewController code:
#interface PA_PhotoTableViewController ()
#property (nonatomic, copy) NSArray *photos;
#end
#implementation PA_PhotoTableViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.photos = [[PA_PhotoStore sharedPhotoStore] allPhotos];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [[[PA_PhotoStore sharedPhotoStore] allPhotos] count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
PA_PhotoCell *cell = [tableView dequeueReusableCellWithIdentifier:#"PhotoCell" forIndexPath:indexPath];
PA_Photo *photo = (self.photos)[indexPath.row];
cell.photoTitle.text = photo.title;
cell.photoOwnerName.text = [NSString stringWithFormat:#"%#", photo.owner];
cell.photoLikes.text = #"99";
// Photo Image URL
NSURL *photoImageURL = [NSURL URLWithString:photo.image_full_url];
[cell.photoImage sd_setImageWithURL:photoImageURL placeholderImage:[UIImage imageNamed:#"lightGraySpinningLoader.gif"]];
// Photo Owner Image
[cell.photoOwnerImage sd_setImageWithURL:photoImageURL placeholderImage:[UIImage imageNamed:#"lightGraySpinningLoader.gif"]];
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
// This code never gets called when I try to tap on a cell
NSLog(#"A row was selected");
}
- (void)dealloc {
NSLog(#"dealloc called in PA_PhotoTableViewController");
}
and here is the custom cell code PA_PhotoCell (consolidated .h & .m files):
#interface PA_PhotoCell : UITableViewCell
#property (nonatomic, weak) IBOutlet UIImageView *photoImage;
#property (nonatomic, weak) IBOutlet UILabel *photoTitle;
#property (nonatomic, weak) IBOutlet UILabel *photoOwnerName;
#property (nonatomic, weak) IBOutlet UIImageView *photoOwnerImage;
#property (nonatomic, weak) IBOutlet UILabel *photoLikes;
#property (nonatomic, weak) IBOutlet UILabel *photoTimestamp;
#property (nonatomic, weak) IBOutlet UILabel *photoComments;
#end
#implementation PA_PhotoCell
- (void)setSelected:(BOOL)selected animated:(BOOL)animated {
[super setSelected:selected animated:animated];
NSLog(#"in set selected");
}
-(void)setHighlighted:(BOOL)highlighted {
NSLog(#"in set highlighted");
}
You can see a few NSLog() calls to help me see if anything is getting called.
Where am I going wrong? The end goal is to click on one of the TableViewCell instances and launch a UINavigationController, I know how to do that, but I can't move on to that step until I figure out why my UITableView won't scroll, and why it disappears when I click on it!
EDIT: After much testing, debugging and experimentation, I have been able to conclude that the problem is actually not with the UITableView at all, and it is, in fact, a problem with how the UITableView is being loaded into its parent view. I still haven't found a solution to my problem, but I am getting closer to finding the cause. Here is what I have discovered:
First, when any of the UIButtons at the bottom of the screen are tapped (see photo reference), it loads the relevant instance of UIViewController into a UIView called placeholderView. When I run my problematic UITableView OUTSIDE of this UIView (where the UITableViewController is acting on its own, not embedded within another UIView) then the table works perfectly, it scrolls, it revives click events, and so on. So as soon as I load the UITableView into the UIView, the UITableView becomes unresponsive (it doesn't scroll or receive tap events) and any attempt to interact with it, the UITableView goes completely blank. My debugging session concludes that the NSArray *photos never gets reset to nil, or manipulated in anyway, the table just goes blank.
So does anyone have any ideas on what would cause a UITableView to do this when being loaded into a generic UIView? All the other views that get loaded into this generic UIView are responsive, and behave as expected. Its just this UITableView that is giving me problems.
If you review the graphic I attached to this post (above), you will see that I am using what appears to be a UITabBarView, but it is, in fact, just a generic view with UIButtons inside. The reason I decided to craft my own "UITabBarView look-alike" instead of using the ready-made UITAbBarView class was because I wanted to give custom functionality to the "menu" button on the bottom left (I want a nice UIView to slide in from the left, and stop about 60 pixels from the right of the screen when the "menu" button is tapped, and I can't figure out how to customize the behavior of the UITabBarView, so I opted for this approach.
Here is the code that is actually loading the UITableViewController into the subview (via a CustomStoryboardSegway):
// PA_HomeViewCustomStoryboardSegue.m
#import "PA_HomeViewCustomStoryboardSegue.h"
#import "PA_HomeViewController.h"
#implementation PA_HomeViewCustomStoryboardSegue
// to create a custom segue, you have to override the perform method
-(void)perform {
// get the source and destination view controllers
PA_HomeViewController *segueSourceController = (PA_HomeViewController *)[self sourceViewController];
UIViewController *destinationController = (UIViewController *)[self destinationViewController];
for (UIView *view in segueSourceController.placeholderView.subviews){
[view removeFromSuperview];
}
segueSourceController.currentViewController = destinationController;
[segueSourceController.placeholderView addSubview:destinationController.view];
}
#end
and here is the header file for my PA_HomeViewController (the view the contains the "placeholderView" which is the target view that loads the various UIViewControllers after the user has tapped the UIButtons at the bottom of the view (similar to a TabBarView) :
#interface PA_HomeViewController : UIViewController
#property (weak, nonatomic) IBOutlet UIView *placeholderView;
#property (weak, nonatomic) UIViewController *currentViewController;
#end
I am hoping that I am just missing something obvious in the way that I am loading the UITableView into the placeholderView, and something in there is causing the UITableView to go completely blank.
When you display the UITableView in a different view, you must always make sure that the view controller which "hosts" the UITableView has a strong reference to its controller. In your case, the data source for the UITableView seems to be deallocated after adding the UITableView as subview.
Changing the currentViewController property from weak to strong should fix your problem.
In swift you need to declare viewcontroller object globally that would result in Strong, in case if you declare locally it results in keep disappearing the cells.
e.g.
var refineViewController : RefineViewController?
then you can access that controller using below code that would not result in disappearing cells.
func showRefineView(isFindHomeTab isFindHomeTab : Bool){
refineViewController = RefineViewController(nibName: String(BaseGroupedTableVC),bundle : nil)
refineViewController!.refineSearchDelegate = self
refineViewController!.view.frame = CGRectMake(0, -490, self.view.frame.size.width, self.view.frame.size.height)
UIView.animateWithDuration(0.3, delay: 0.0, options: .CurveEaseOut, animations:
{
self.refineViewController!.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)
self.refineViewController!.isFindHomeTab = isFindHomeTab
}, completion: nil)
self.view.addSubview(refineViewController!.view)
}
I experienced the exact same problem. The issue was that I was using a custom datasource class (called tableVCDataSource), and was setting the tableView's dataSource incorrectly in the ViewController class. I was doing:
override func viewDidLoad() {
mainTableView.dataSource = TableVCDataSource()
}
when I should have been doing:
fileprivate var tableVCDataSource: TableVCDataSource?
override func viewDidLoad() {
tableVCDataSource = TableVCDataSource()
mainTableView.dataSource = tableVCDataSource
}
This solved my issue.
I've read quite a few tutorials online about how to create a custom cell subclass, but I'm still a little confused. When I try to follow the instructions found in this question, I end up with errors that the tableView is not a valid property for the object of ViewController.
I've created a new subclass of UITableViewCell, called CustomBookClass. I've hooked up the properties with my CustomBookClass.h file.
#import <UIKit/UIKit.h>
#interface CustomBookCell : UITableViewCell
#property (weak, nonatomic) IBOutlet UIImageView *bookImage;
#property (weak, nonatomic) IBOutlet UILabel *bookTitle;
#property (weak, nonatomic) IBOutlet UILabel *dateAdded;
#end
I then go into my ViewController.m file to edit the viewDidLoad method.
- (void)viewDidLoad
{
[super viewDidLoad];
[self.tableView.delegate = self];
[self.tableView.dataSource=self];
[self.tableView registerClass:[CustomBookCell class]forCellReuseIdentifier:#"Custom
Cell"];
}
I get an error on the tableView, saying the property doesn't exist, even though in the ViewController.h file, I'm including the table view.
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController <UITableViewDelegate,
UITableViewDataSource>
#end
I'm sure I'm missing something really obvious here, as this is my first time trying this. Can anyone help me out? Thanks!
UIViewController does not have that property. Even if you assign the Delegate and DataSource protocols to it. There are a couple of things you can do however.
Link the table view to the ViewController yourself. That means, create a property/outlet called tableView.
Inherit from UITableViewController instead of UIViewController.
Both should work.
Edit: Oh and the lines:
[self.tableView.delegate = self];
[self.tableView.dataSource=self];
don't make sense. They should be either:
self.tableView.delegate = self; and self.tableView.dataSource = self;
Or [self.tableView setDelegate:self]; and [self.tableView setDataSource:self]
with 1 being preferred. (Edit: option #2 was actually incorrect code, my bad.)
No need to set delegate and datasource in TableViewCell class
simple make a property and synthesize your table view item
#property (weak, nonatomic) IBOutlet UIImageView *bookImage;
#property (weak, nonatomic) IBOutlet UILabel *bookTitle;
#property (weak, nonatomic) IBOutlet UILabel *dateAdded;
now import your cell class in your tableView controller class
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *simpleTableIdentifier = #"SimpleTableCell";
SimpleTableCell *cell = (SimpleTableCell *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
if (cell == nil)
{
//If you are using xib for representing your UI then add a nib file.
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"SimpleTableCell" owner:self options:nil];
cell = [nib objectAtIndex:0];
}
cell.bookTitle.text = [tableData objectAtIndex:indexPath.row];
cell.bookImage.image = [UIImage imageNamed:[thumbnails objectAtIndex:indexPath.row]];
cell.dateAdded.text = [prepTime objectAtIndex:indexPath.row];
return cell;
}
for more detail check this link
I have a UITableView that covers the whole screen, with a lot of cells.
On the view that holds the UITableView I want to display an UIImage at the top right corner.
This UIImage (or UIImageView) is fixed on the UIView - it is not part of the tableView (in the z order it is over the tableView).
It is possible to let the UITableView float around this image, even when scrolling?
Below an image of my desired structure. Imagine that they are more cells even under der image. The cells (or UILabels) that are covered by the image should be truncated (or do a line break).
Is this possible? Currently I have no idea how to do this.
One option is to adjust the trailing space constraint of a label on your custom table view cell based on tableview's scrollview delegate method. You need to check if your cell is in the area of your imageView and then adjust the constraint. You also need to adjust the constraint in your cellForRowAtIndexPath for the initial layout.
Storyboard
ViewController.m
#import "ViewController.h"
#import "MyCell.h"
#interface ViewController () <UITableViewDataSource, UITableViewDelegate>
#property (weak, nonatomic) IBOutlet UITableView *tableView;
#property (weak, nonatomic) IBOutlet UIImageView *imageView;
#end
#implementation ViewController
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 20;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
MyCell *cell = (MyCell *)[tableView dequeueReusableCellWithIdentifier:#"MyCell" forIndexPath:indexPath];
// Configure the cell...
cell.myLabel.text = #"Lorem ipsum dolor sit amet, etc.";
if (indexPath.row >=3 && indexPath.row <= 5) {
cell.trailingSpaceConstraint.constant = 168;
}
return cell;
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
NSUInteger count = 0;
for (MyCell *cell in [self.tableView visibleCells]) {
if (count >= 3 && count <= 6) {
cell.trailingSpaceConstraint.constant = 168.0;
} else {
cell.trailingSpaceConstraint.constant = 20.0;
}
count++;
}
}
#end
MyCell.h
#import <UIKit/UIKit.h>
#interface MyCell : UITableViewCell
#property (weak, nonatomic) IBOutlet UILabel *myLabel;
#property (weak, nonatomic) IBOutlet NSLayoutConstraint *trailingSpaceConstraint;
#end
Output
In this sample you need to use custom ViewController, add tableView and imageView, hook tableView's delegate and datasource and outlet. You also need to add custom subclass of UITableViewCell (MyCell) and hook outlets of the cell's label and the trailing space constraint.
The check at scrollViewDidScroll for rows is quick and dirty. Probably a better solution might be to check which cells are touching the imageView rect in indexPathsForRowsInRect.