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I am using collection view to showing the taken images of my app.I want as soon as the image taken the collection view should automatically move to last object in my collection view .My collection scrolls horizontally
Please help me to do this.
I have searched in google and i have found i have applied this code in my project
i have applied this code in my project in viewwillappear ,it showing error,
Please help me to do this
click here to see i am taking photo and showing in below ,ok ,in this image it has 3pictures ,if i again take a picture 4th picture will be there in collection view ,if user want to se the 4th picture means ,user want scroll by manually and can see it...
Here is my code:
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[[self navigationController] setNavigationBarHidden:NO animated:YES];
[session startRunning];
NSInteger section = [self numberOfSectionsInCollectionView:self.collection_View] - 1;
NSInteger item = [self collectionView:self.collection_View numberOfItemsInSection:section] - 1;
NSIndexPath *lastIndexPath = [NSIndexPath indexPathForItem:item inSection:section];
}
I want automatically scroll to the last pictures in horizontally
Thanks in Advance !!!
Add the following line inside your viewWillAppear method code:
[collectionView scrollToItemAtIndexPath:lastIndexPath atScrollPosition:UICollectionViewScrollPositionBottom animated:YES];
Use this:
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[[self navigationController] setNavigationBarHidden:NO animated:YES];
[session startRunning];
NSInteger section = [self numberOfSectionsInCollectionView:self.collection_View] - 1;
NSInteger item = [self collectionView:self.collection_View numberOfItemsInSection:section] - 1;
NSIndexPath *lastIndexPath = [NSIndexPath indexPathForItem:item inSection:section];
[collectionView scrollToItemAtIndexPath:lastIndexPath atScrollPosition:UICollectionViewScrollPositionBottom animated:YES];
}
Here's the Swift 4.2 version of the accepted answer
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let section = numberOfSections(in: collectionView) - 1
let item = collectionView.numberOfItems(inSection: section) - 1
let lastIndexPath = IndexPath(item: item, section: section)
collectionView.scrollToItem(at: lastIndexPath, at: .bottom, animated: true)
}
I got a really strange problem.
My tableView has all the delegate and datasource set up.
Everything is fine.
However, clicking the rows do not activate:
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
I used custom cells.
After I click and click and click and click and click, sometimes it goes through.
I wonder what can possibly cause that? It's as if the customCell is "absorbing" the touch event or something or what?
Could that be why? If so, if we want to implement customCell and we want the tableView to handle the touch up event, what should we do?
Additional symptom:
If I remove user interaction enabled from the custom cell then the problem is solved with a catch.
However, clicking the button will somehow erase all the label texts in the customCell.
The implementation of the custom Cell is the following:
- (BGUIBusinessCellForDisplay *) initWithBiz: (Business *) biz
{
if (self.biz == nil) //First time set up
{
self = [super init]; //If use dequeueReusableCellWithIdentifier then I shouldn't change the address self points to right
NSString * className = NSStringFromClass([self class]);
//PO (className);
[[NSBundle mainBundle] loadNibNamed:className owner:self options:nil];
self.frame =self.view.frame;
[self addSubview:self.view]; //What is this for? self.view is of type BGCRBusinessForDisplay2. That view should be self, not one of it's subview Things don't work without it though
}
if (biz==nil)
{
return self;
}
_biz = biz;
self.prominentLabel.text = [NSString stringWithFormat:#"Isi: %#", biz.isiString];
self.Title.text = biz.Title; //Let's set this one thing first
self.Address.text=biz.ShortenedAddress;
//if([self.distance isNotEmpty]){
self.DistanceLabel.text=[NSString stringWithFormat:#"%dm",[biz.Distance intValue]];
self.PinNumber.text =biz.StringPinLineAndNumber;
NSString * URLString=nil;
if(biz.Images.allObjects.count!=0){
//self.boolImage=[NSNumber numberWithBool:true];
Image * image=(biz.Images.allObjects)[0];
URLString = image.URL;
URLString = [NSString stringWithFormat:#"http://54.251.34.144/thumbnailer/Thumbnailer.ashx?imageURL=%#",URLString.UTF8Encode];
//url=[NSURL URLWithString:image.URL];
}else{
float latitude = biz.getCllLocation.coordinate.latitude;
float longitude = biz.getCllLocation.coordinate.longitude;
URLString = [NSString stringWithFormat:#"http://maps.googleapis.com/maps/api/staticmap?&zoom=16&size=160x160&maptype=roadmap&sensor=true¢er=%f,%f&markers=size:small|color:blue|%f,%f",latitude,longitude,latitude,longitude];
URLString = URLString.UTF8Encode;
}
//Should add code and add loading indicator here
[BGHPTools doBackground:^{
UIImage * imageBiz = [BGMDImageCacherAndDownloader getImageFromURL:URLString];
[BGHPTools doForeGround:^{
self.Image.image=imageBiz;
[self.Image makeRound];
}];
}];
//self.view=self.view;
/*if (self.tableViewCell == Nil)//Instantiate that tableviewCell
{
PO(self.tableViewCell);
}
self.tableViewCell.business = bis;
self.pinLbl.text = bis.StringPinLineAndNumber;
self.lblTitle.text=bis.Title;
//self.pinLbl.text=bis.pinNumber;*/
//}
/*self.name=[dict objectForKey:#"Title"];
self.address=[dict objectForKey:#"Street"];
CLLocation * cll=[[CLLocation alloc]initWithLatitude:[[dict objectForKey:#"Latitude"] doubleValue] longitude:[[dict objectForKey:#"Longitude"] doubleValue]];
self.distance=[NSNumber numberWithDouble:[cll distanceFromLocation:[cachedProperties currentLocation]]];*/
return self;
Update: I already figure out why the texts are gone. Turns out my background is white. When a row got selected, the text suddenly turn into white. So by setting selected style to blue I sort of get that "fixed".
However, I still do not see where in my code I specify that all label texts should be white if the underlying tableViewCell is selected.
After all, what's selected is the cell, not the label. How the hell the label knows that it has to turn white is beyond me.
If you are using a Storyboard to handle the interface, instead of using:
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
Try using
#pragma mark --- Push selectedObject to the detailView ---
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
RRAppDelegate *myAppDelegate = [[UIApplication sharedApplication]delegate];
if ([[segue identifier] isEqualToString:#"PushObjectSegue"]) {
NSIndexPath *selectedRowIndex = [self.tableView indexPathForSelectedRow];
RRObjectViewController *detailViewController = [segue destinationViewController];
detailViewController.selectedObject = [myAppDelegate.goals objectAtIndex:selectedRowIndex.row];
}
}
I was having the same problem with the method you used and instead used this, it started working perfectly. Of course you'd have to adapt the code to your app's viewControllers and data source because I used my AppDelegate as the datasource, and I wasn't using a custom cell.
The most likely thing is that a view in your custom cell is absorbing the touch. Sometimes this is what you want, e.g. a button that does something, rather than selecting the entire cell. Assuming you don't want this, then just set those views' userInteractionEnabled property to NO.
--Additional code for custom NIB loading.
All you have to do is register the NIB in your viewDidLoad routine:
[tableView registerNib: [UINib nibWithNibName:#"yourCellNibName" bundle:nil] forCellReuseIdentifier:#"yourCellTypeID"]
and then in your cellForRowAtIndexPath just call:
newCell = [tableView dequeueReusableCellWithIdentifier #"yourCellTypeID"];
...
return newCell;
And it will load a cell from your XIB (or give you one from the previously used queue).
I just want to update that I think I have figured out what the problem is but still can't solve that quite right yet. And well the update is comprehensive so I think it should be an answer though I hope it's not the answer because some puzzle is still missing.
All the problem is interrelated.
The problem is in this line:
[self addSubview:self.view];
I basically turn that into:
Basically the my custom view cell has a view whose type is also tableViewCell. That view cover the real tableViewCell.
That's why when user interaction is enabled, that view will absorb the user's interaction.
That's also why the label "disappear". What happen is the label doesn't disappear. The label got highlighted and become white. However, what's highlighted is the tableViewCell not the opague view. The white opague self.view is still white while the tableCell itself is tinted with blue. So the label becomes white in the middle of white background and is gone.
I think I should replace [self addSubview:self.view] into self= self.view
However, that would mean changing the value of self. Yes it's in init. But it's still awkward. If anyone has the WAY to implement custom subclass of UI with XIB it'll be great because I haven't found one till now.
Awkward.
I wonder if we can draw a pointer to an XIB and specify that the outlet is self itself.
If that fail, I'll set background of self to white and background of self.view to transparent.
After tons of error and trying I did this:
self.contentView.backgroundColor = [UIColor whiteColor];
//self.view.backgroundColor = [UIColor redColor];
self.frame =self.view.frame;
/*PO(self.view.subviews);
PO(self.subviews);
PO(self.Title.superview);
PO(self.Title);
PO(self.view);
PO(self.Title.superview);
PO(self.view.contentView);*/
//Suck all the subviews from my minions
for (UIView* aSubView in self.view.contentView.subviews) {
[self.contentView addSubview: aSubView];
//[self.contentView add]
}
Basically I "move" all the subViews of my view object to my self object. There is a catch though that when subclassing tableViewCell I should move the subviews of the contentView. Who knows why.
At the end I just set self.view to nil for it's no longer needed and my program works as expected.
Also to set background of your tableViewCell, you need also to set the background of self.contentView rather than self.view.
Another approach you can try is to use story board. Alternatively you can just move the contentView of the self.view to self.
Make sure you'r implementing that method and not
deselectRowAtIndexPath:animated
This morning I just installed new Xcode which includes iOS 6.
I have a table view loaded with a plist file containing chapters and lines. Chapters define the sections.
The user selects chapter and line and the tableview is automatically scrolled to the correct position (in the viewDidLoad).
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:linePos inSection:chapterPos];
[self.tableView scrollToRowAtIndexPath:indexPath
atScrollPosition:UITableViewScrollPositionTop animated:YES];
this works just great in iOS5 simulator.
Trying this in the iOS 6 simulator the scroll is not performed. I get no errors. I have checked, linePos and chapterPos receive correct values but the scroll is not performed.
Any ideas why ?
Objective-C:
[self.tableView reloadData];
dispatch_async(dispatch_get_main_queue(), ^{
NSIndexPath *rowIndexPath = [NSIndexPath indexPathForRow:3 inSection:0];
[self.tableView scrollToRowAtIndexPath:rowIndexPath atScrollPosition:UITableViewScrollPositionMiddle animated:YES];
});
Swift:
tableView.reloadData()
DispatchQueue.main.async {
let indexPath = IndexPath(row: linePos, section: chapterPos)
self.tableView.scrollToRow(at: indexPath, at: .top, animated: true)
}
For recent versions of iOS, please read Fyodor Volchyok's answer. Note that it's not marked as the accepted answer simply because at the time the question was first asked (Sept. 2012), the current answer was the working solution.
More recent versions of iOS also got the same problem which is now solved by Fyodor Volchyok's answer, so you should +1 his answer at that moment.
I found the answer. I have to first reload the data in the tableview
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:linePos inSection:chapterPos];
[self.tableView reloadData];
[self.tableView scrollToRowAtIndexPath:indexPath
atScrollPosition:UITableViewScrollPositionTop animated:YES];
Even though I found the answer I don't know why it is working in iOS5 and not in iOS6.
EDIT
Perhaps I should add that even though it was working, I was still having a problem in displaying the last row and posted a question for that
UItableview scrollToRowAtIndexPath not displaying last row correctly
As #Raj also asked for it, I should say that I was triggering that in the viewDidLoad. To correct the problem of the last row not displaying correctly I had to put it in the viewDidAppear.
This works in iOS 12 and 13:
DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
self.tableView.scrollToRow(at: IndexPath(row: 0, section: 1), at: .bottom, animated: true)
}
I ran into another issue (probably a bug) with scrollToRowAtIndexPath specifically on an iPhone X running ios11. My table has a few hundred sections and in collapsed mode ~10 would fit in the visible screen. As the indexPath got deeper, the scrolling gradually fell behind.
For example, when I wanted the search to find the item in row 30, the ScrollPositionTop would have one additional row before the actual row I expect to be at the top.
And as I tested searching for deeper rows, it started falling behind even more where for say anything past 100 rows deep or so, the expected row did not even come in the visible area.
The workaround I found so far is to say animated:NO for the scrolling within dispatch_async, then it works without any glitches.
I'm adding this answer as an addition to Fyodor Volchyok's answer. I also found that dispatching solves the issue. I was able to find a workaround that doesn't dispatch.
self.tableView.reloadData()
let index = // the desired index path
// For some reason, requesting the cell prior to
// scrolling was enough to workaround the issue.
self.tableView.cellForRowAtIndexPath(index)
self.tableView.scrollToRowAtIndexPath(index, atScrollPosition: .Top, animated: false)
After iOS7 the property automaticallyAdjustsScrollViewInsets of UIViewController default is YES. It will cause system to adjust the contentOffset of tableView when the view controller pushed. Even you call [self.tableView scrollToRowAtIndexPath:rowIndexPath atScrollPosition:UITableViewScrollPositionNone animated:NO]; in the viewWillAppear. The contentOffset also will be changed by system after viewWillAppear. So my solution is:
- (void)viewDidLoad {
[super viewDidLoad];
self.automaticallyAdjustsScrollViewInsets = NO;
/// any other codes
}
- (void)viewWillLayoutSubviews {
self.tableView.contentInset = UIEdgeInsetsMake(self.topLayoutGuide.length, 0, 0, 0);
}
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
// change tableView data source
[self.tableView reloadData];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:[self.dataSourceArray count] - 1 inSection:0];
[self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionNone animated:NO];
}
One more possible workaround is to call layoutIfNeeded before calling scrollToRowAtIndexPath.
[self.view layoutIfNeeded];
[self.tableView scrollToRowAtIndexPath...];
It worked for me in ios11
self.tableView.estimatedRowHeight = 0;
self.tableView.estimatedSectionFooterHeight = 0;
self.tableView.estimatedSectionHeaderHeight = 0
dispatch_async(dispatch_get_main_queue(), ^{
NSInteger numberOfSections = self.tableView.numberOfSections;
if (numberOfSections > 0)
{
NSInteger lastSection = numberOfSections - 1;
NSInteger lastRowInLastSections = [self.tableView numberOfRowsInSection:lastSection] - 1;
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:lastRowInLastSections inSection:lastSection];
[self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionBottom animated:isAnimated];
}
});
Fyodor Volchyok's answer in Swift:
tableView.reloadData()
let indexPath = NSIndexPath(forRow: linePos, inSection: chapterPos)
// make sure the scroll is done after data reload was finished
dispatch_async(dispatch_get_main_queue()) {
self.tableView.scrollToRowAtIndexPath(indexPath, atScrollPosition: .Top, animated: true)
}
Maybe it's a similar beginning, but it's true.
first of all sorry if this isn't formatted correctly, first time doing this. I've been using stackoverflow to find help for a long time now and it's been very helpful (thank you all), but this is the first time I've posted a question of my own. This question has been asked many times, but when I call [self.tableView reloadTable] the methods numberOfSectionsInTableView and numberOfRowsInSection are called but not cellForRowAtIndexPath.
Every answer I've seen when searching has been a variation of:
The tableView is nil
numberOfRowsInSection is 0
tableView's delegate/data source not set. None of these are the case for me so I'm wondering what else could be wrong.
But I'm not sure 4. calling reloadTable on the wrong uiTableView. Or it's about some other false.
Now my APP is similar to dropbox,
first when we log into it, we get a file list(include directories) in the TableView.also, I added a toolbar in the bottom of the view by [self.navigationController.view addSubview:toolBar], when I touch the button item "refresh", it calls [self.tableView reloadData] and works well.
Second when we select a directory we will get a new file list table which is pushViewController by self.navigationController, but this time when we touch the "refresh", the statement [self.tableView reloadData] calls numberOfSections, numberOfRows, not cellForRowAtIndexPath
Any ideas as to why cellForRow's not being called the Second time? Thanks in advance.
FileListViewController.h
#interface FileListViewController : UITableViewController <UITableViewDelegate, UITableViewDataSource>
FileListViewController.m
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
if (isDir) {
FileListViewController *fileListViewController = [[FileListViewController alloc] init];
[self.navigationController pushViewController:fileListViewController animated:YES];
}
}
- (void)refresh
{
[Utilities refresh];//Utilities is my custom class.
[self viewDidLoad];
[self.tableView reloadData];
}
My return number of section and row in table view is not 0.
When I added NSLog(#"Calling reloadData on %#", self.tableView); into "refresh":
- (void)refresh
{
[Utilities refresh];//Utilities is my custom class.
[self viewDidLoad];
NSLog(#"Calling reloadData on %#", self.tableView);
[self.tableView reloadData];
}
Then it returns Calling reloadData on ; contentOffset: {0, 0}>. Delegate: FileListViewController, DataSource: FileListViewController
You should not manually call [self viewDidLoad]. This method is designed to be overridden, and is automatically called. For more information, please read this documentation.
I have a custom UITableView using UITableViewCells.
Each UITableViewCell has 2 buttons. Clicking these buttons will change an image in a UIImageView within the cell.
Is it possible to refresh each cell separately to display the new image?
Any help is appreciated.
Once you have the indexPath of your cell, you can do something like:
[self.tableView beginUpdates];
[self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:indexPathOfYourCell, nil] withRowAnimation:UITableViewRowAnimationNone];
[self.tableView endUpdates];
In Xcode 4.6 and higher:
[self.tableView beginUpdates];
[self.tableView reloadRowsAtIndexPaths:#[indexPathOfYourCell] withRowAnimation:UITableViewRowAnimationNone];
[self.tableView endUpdates];
You can set whatever your like as animation effect, of course.
I tried just calling -[UITableView cellForRowAtIndexPath:], but that didn't work. But, the following works for me for example. I alloc and release the NSArray for tight memory management.
- (void)reloadRow0Section0 {
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
NSArray *indexPaths = [[NSArray alloc] initWithObjects:indexPath, nil];
[self.tableView reloadRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationNone];
[indexPaths release];
}
Swift:
func updateCell(path:Int){
let indexPath = NSIndexPath(forRow: path, inSection: 1)
tableView.beginUpdates()
tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic) //try other animations
tableView.endUpdates()
}
reloadRowsAtIndexPaths: is fine, but still will force UITableViewDelegate methods to fire.
The simplest approach I can imagine is:
UITableViewCell* cell = [self.tableView cellForRowAtIndexPath:indexPath];
[self configureCell:cell forIndexPath:indexPath];
It's important to invoke your configureCell: implementation on main thread, as it wont work on non-UI thread (the same story with reloadData/reloadRowsAtIndexPaths:). Sometimes it might be helpful to add:
dispatch_async(dispatch_get_main_queue(), ^
{
[self configureCell:cell forIndexPath:indexPath];
});
It's also worth to avoid work that would be done outside of the currently visible view:
BOOL cellIsVisible = [[self.tableView indexPathsForVisibleRows] indexOfObject:indexPath] != NSNotFound;
if (cellIsVisible)
{
....
}
If you are using custom TableViewCells, the generic
[self.tableView reloadData];
does not effectively answer this question unless you leave the current view and come back. Neither does the first answer.
To successfully reload your first table view cell without switching views, use the following code:
//For iOS 5 and later
- (void)reloadTopCell {
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
NSArray *indexPaths = [[NSArray alloc] initWithObjects:indexPath, nil];
[self.tableView reloadRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationNone];
}
Insert the following refresh method which calls to the above method so you can custom reload only the top cell (or the entire table view if you wish):
- (void)refresh:(UIRefreshControl *)refreshControl {
//call to the method which will perform the function
[self reloadTopCell];
//finish refreshing
[refreshControl endRefreshing];
}
Now that you have that sorted, inside of your viewDidLoad add the following:
//refresh table view
UIRefreshControl *refreshControl = [[UIRefreshControl alloc] init];
[refreshControl addTarget:self action:#selector(refresh:) forControlEvents:UIControlEventValueChanged];
[self.tableView addSubview:refreshControl];
You now have a custom refresh table feature that will reload the top cell. To reload the entire table, add the
[self.tableView reloadData]; to your new refresh method.
If you wish to reload the data every time you switch views, implement the method:
//ensure that it reloads the table view data when switching to this view
- (void) viewWillAppear:(BOOL)animated {
[self.tableView reloadData];
}
Swift 3 :
tableView.beginUpdates()
tableView.reloadRows(at: [indexPath], with: .automatic)
tableView.endUpdates()
Here is a UITableView extension with Swift 5:
import UIKit
extension UITableView
{
func updateRow(row: Int, section: Int = 0)
{
let indexPath = IndexPath(row: row, section: section)
self.beginUpdates()
self.reloadRows(at: [indexPath], with: .automatic)
self.endUpdates()
}
}
Call with
self.tableView.updateRow(row: 1)
Just to update these answers slightly with the new literal syntax in iOS 6--you can use Paths = #[indexPath] for a single object, or Paths = #[indexPath1, indexPath2,...] for multiple objects.
Personally, I've found the literal syntax for arrays and dictionaries to be immensely useful and big time savers. It's just easier to read, for one thing. And it removes the need for a nil at the end of any multi-object list, which has always been a personal bugaboo. We all have our windmills to tilt with, yes? ;-)
Just thought I'd throw this into the mix. Hope it helps.
I need the upgrade cell but I want close the keyboard.
If I use
let indexPath = NSIndexPath(forRow: path, inSection: 1)
tableView.beginUpdates()
tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic) //try other animations
tableView.endUpdates()
the keyboard disappear