I am having a collection view which shows 3 cells as visible. when i click the right arrow button, It should scroll to show the next 3 cells and when i click the left arrow button, It should scroll to show the previous 3 cells. In case if there is 2 cells behind, it should show those 2 cells with previous last visible cell.
can someone help with it?
You just need to do
[self.collectionView scrollToItemAtIndexPath:nextItem atScrollPosition:UICollectionViewScrollPositionBottom animated:YES];
where you need to pass indexpath for next item you want to scroll
I have found the solution.
- (void)viewDidLoad
{
oldrow=0;
}
- (IBAction)right_button:(id)sender
{
NSIndexPath *newIndexPath;
if (xr-1>0) {
oldsection = 0;
newIndexPath = [NSIndexPath indexPathForRow:oldrow+3 inSection:0];
oldrow=oldrow+3;
[collection_vw scrollToItemAtIndexPath:newIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
xr--;
xl++;
}
else if (y>0)
{
[_btn_right setHidden:YES];
oldsection = 0;
newIndexPath = [NSIndexPath indexPathForRow:array_stories.count-3 inSection:0];
oldrow=array_stories.count-3;
[collection_vw scrollToItemAtIndexPath:newIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
}
}
where
xr=array_stories.count/3;
xl=0;
y=array_stories.count%3;
Related
I have a UITableView with custom UITableViewCell and datasource.
My tableviewdelegate class is registered to callback on on an event and once I got the event, I am reloading the data on the tableview.
The call back comes after I edit the tableviewcell data. But once the callback came, when I reloaddata, the tableview is scrolling to the top; and not staying at the current selection.
So I have cached the current selected cell and trying to scrollToRowAtIndexPath.
But I am hitting a crash.
How can I scroll to that row after tabledata is loaded ?
{
[m_tableView reloadData];
if(m_currentEditingCell != nullptr)
{
[m_tableView scrollToRowAtIndexPath:m_currentEditingCell atScrollPosition:UITableViewScrollPositionNone animated:YES];
}
}
You should provide NSIndexPath instead of providing your tableviewcell as argument for the selector scrollToRowAtIndexPath:atScrollPosition: animated:
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[yourTableView scrollToRowAtIndexPath:indexPath
atScrollPosition:UITableViewScrollPositionTop
animated:YES];
The following code is able to select the cell after reload.
{
[m_tableView reloadData]; dispatch_async(dispatch_get_main_queue(), ^{ NSIndexPath* indexPath = [NSIndexPath indexPathForRow: ([m_tableView numberOfRowsInSection:([m_tableView numberOfSections]-1)]-1) inSection:([m_tableView numberOfSections]-1)]; if(m_currentCell != nullptr ) [self selectCurrentCell:m_currentCell];
}
}
I have a UICollectionView and its cells contains questions and UITextField that users must write in. I want to add a button onto the UICollectionViewCell, that the users must press that will scroll them to the next UICollectionViewCell. Is this possible and how do I do this.
You can set the button tag to hold the value of the index row.
So in your cellForRowAtIndexPath method add:
cell.nextButton.tag = indexPath.row
Then to scroll to a certain index you can call this when the button is pressed:
[self.collectionView scrollToItemAtIndexPath:indexPath atScrollPosition:UICollectionViewScrollPositionCenteredVertically animated:YES];
Sorry It's late, But today I am working on same functionality.
Please use below code and it's working.
1) Add line in cellForItemAtIndexPath.
btnNext.tag = indexPath.item;
2) Create method for scroll to next cell.
-(IBAction)actionNext:(UIButton *)sender{
if(sender.tag == 0 || sender.tag == nil){
btnNext.tag = 1;
}
if(sender.tag > arrImage.count){
[self.colView scrollToItemAtIndexPath:[NSIndexPath indexPathForRow:arrImage.count-1 inSection:0] atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:YES];
}else{
[self.colView scrollToItemAtIndexPath:[NSIndexPath indexPathForRow:sender.tag inSection:0] atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:YES];
}
}
Please ask me if you have any question. :)
I am making a chat application. When the keyboard appears, my UITableView and toolbar (with textfield and button) move up using the setFrame method.
The problem occurs when I am receiving a message from another user while I'm typing a message. When that happens (i.e. after an insertRowsAtIndexPaths to the UITableView), my UITableView and toolbar "reset" to their original positions.
Is this normal behavior caused by the system? I can't find anything in my code that would do this. I want that the toolbar remains visible so I can still type my message.
This is the code to add a convoItem (conversation item) to my array and UITableView:
- (void)insertConvoItem:(ConvoItem *)item
{
[_convoItems addObject:item];
// Update the table view
NSIndexPath *newIndexPath = [NSIndexPath indexPathForRow:([self.convoItems count] - 1) inSection:0];
[self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
// Scroll to the bottom so we focus on the latest message
NSUInteger numberOfRows = [self.tableView numberOfRowsInSection:0];
if (numberOfRows) {
[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:(numberOfRows - 1) inSection:0] atScrollPosition:UITableViewScrollPositionBottom animated:YES];
}
}
It's normal. Receiving new message resets your table view to it's original position.
I am using [tableview reloadData]; to reload the data in my UItableView, however when I use this I loose my highlight on my UItableVewCell.
I would like to know the best way to reinstate this highlight.
I set a tempIndexPath when the user selects the cell they edit the information then I call reloadData, then inside cellForRowAtIndexPath I use this code to re-highlight the cell however its not working.
if ([tempIndexPath isEqual:indexPath]) {
cell.selected = YES;
}
This code keeps the highlighted selection, and is safe with resorting/inserts/repositioning since it keeps a reference to the underlying object from the model, instead of the index path. It also scrolls to the selection, which is helpful when the updated model causes the selection to be moved out of the current scroll position's frame.
- (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
//Save the selected object at this row for maintaining the highlight later in reloadData
_selectedItem = [_items objectAtIndex:indexPath.row];
}
- (void) reloadData
{
[_itemsTable reloadData];
//Reselect and scroll to selection
int numItems = _items.count;
for (int i = 0; i < numItems; i++) {
NSDictionary *dict = [_numItems objectAtIndex:i];
if (dict == _selectedItem) {
//This is more reliable than calling the indexPathForSelectedRow on the UITableView,
// since the selection is cleared after calling reloadData
NSIndexPath *selectedIndexPath = [NSIndexPath indexPathForRow:i inSection:0];
[_itemsTable scrollToRowAtIndexPath:selectedIndexPath atScrollPosition:UITableViewScrollPositionMiddle animated:NO];
[_itemsTable selectRowAtIndexPath:selectedIndexPath animated:FALSE scrollPosition:UITableViewScrollPositionNone];
break;
}
}
}
Save the selected row, reload your table view's data and select the row again.
NSIndexPath* selectedIndexPath = [tableView indexPathForSelectedRow];
[tableView reloadData];
[tableView selectRowAtIndexPath:selectedIndexPath animated:NO scrollPosition:UITableViewScrollPositionNone];
You should know that this is dangerous, because if new items were added to the table view before the selected row, the selection will not be the correct cell. You should calculate how many rows were inserted before the row and adjust the selectedIndexPath accordingly.
I have an application that works some what similar to how iPhone's Contact application works. When we add a new Contact user is directed to a view only screen with Contact information. If we select "All Contacts" from the navigation bar, user is navigated to list of all contacts where the recently added contact is in view.
We can move the view to a particular row using:
[itemsTableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionBottom];
... but it's not working. I'm calling this right after calling:
[tableView reloadData];
I think I'm not suppose to call selectRowAtIndexPath:animated:scrollPosition method here. But if not here, then where?
Is there any delegate method that gets called after the following method?
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath;
I think I've got a similar app: A list of item., tap '+' -> new screen, come back and see the updated list, scrolled to show the added item at the bottom.
In summary, I put reloadData in viewWillAppear:animated: and scrollToRowAtIndexPath:... in viewDidAppear:animated:.
// Note: Member variables dataHasChanged and scrollToLast have been
// set to YES somewhere else, e.g. when tapping 'Save' in the new-item view.
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
if (dataHasChanged) {
self.dataHasChanged = NO;
[[self tableView] reloadData];
} else {
self.scrollToLast = NO; // No reload -> no need to scroll!
}
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
if (scrollToLast) {
NSIndexPath *scrollIndexPath = [NSIndexPath indexPathForRow:([dataController count] - 1) inSection:0];
[[self tableView] scrollToRowAtIndexPath:scrollIndexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
}
}
I hope this helps. If you add something in the middle of the list, you could easily scroll to that position instead.
You can try this , my application in some kind of similar to you when i click on a button scroll of uitableview is up.
[tableviewname setContentOffset:CGPointMake(0, ([arrayofcontact count]-10)*cellheight) animated:YES];
10 is for how many cell you want to scroll up
Hope this will help you:-)
Scrolling animation is inevitable when offset is set from viewDidAppear(_:). A better place for setting initial scroll offset is viewWillAppear(_:). You'll need to force the layout of a table view, because it's content size is not defined at that point.
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
tableView.setNeedsLayout()
tableView.layoutIfNeeded()
if let selectedIndexPath = selectedIndexPath, tableView.numberOfRows(inSection: selectedIndexPath.section) > 0 {
tableView.scrollToRow(at: selectedIndexPath, at: .top, animated: false)
}
}
Do you have enough dummy contacts added to test the scrolling? It seems that only when your tableView is of a certain size the iPhone finds the inputus to scroll.
This is the code that works for me in my project. I use a previous button and therefore I scroll the tableview a little bit further down that it usually would go with UITABLEVIEWSCROLLPOSITION. (my previous button won't work if it can't "see" the previous cell.
Ignore some of the custom method calls.
- (void)textFieldDidBeginEditing:(UITextField *)textField {
//Show the navButtons
[self navButtonAnimation];
DetailsStandardCell *cell = (DetailsStandardCell *)textField.superview.superview.superview;
self.parentController.lastCell = cell;
//Code to scroll the tableview to the previous indexpath so the previous button will work. NOTE previous button only works if its target table cell is visible.
NSUInteger row = cell.cellPath.row;
NSUInteger section = cell.cellPath.section;
NSIndexPath *previousIndexPath = nil;
if (cell.cellPath.row == 0 && cell.cellPath.section != 0) //take selection back to last row of previous section
{
NSUInteger previousIndex[] = {section -1, ([[self.sections objectForKey:[NSNumber numberWithInt:section - 1]]count] -1)};
previousIndexPath = [[NSIndexPath alloc] initWithIndexes:previousIndex length:2];
}
else if (cell.cellPath.row != 0 && cell.cellPath.section != 0)
{
NSUInteger previousIndex[] = {section, row - 1};
previousIndexPath = [[NSIndexPath alloc] initWithIndexes:previousIndex length:2];
}
[self.theTableView scrollToRowAtIndexPath: cell.cellPath.section == 0 ? cell.cellPath : previousIndexPath atScrollPosition:UITableViewScrollPositionTop animated:YES];
}