I'm modifying my UITableView's data source from a PHChange instance, and this works fine. What I don't understand is I can't get the sectionIndex on the right of the UITableView to update unless you reload the whole UITableView with: reloadData.
Is there any other way to force update the sectionIndex on the right of the UITableView? If I manually call: sectionIndexTitlesForTableView: I confirm that I'm getting back fresh data, however the old sectionIndex on the right doesn't change visually, which is what I need.
Code:
PHFetchResultChangeDetails *changeDetails = [changeInstance changeDetailsForFetchResult:oldFetch];
if (changeDetails)
{
PHFetchResult *fetchResultAfterChange = changeDetails.fetchResultAfterChanges;
if (fetchResultAfterChange.count < 1)
{
[subArray removeObjectAtIndex:subIdx];
dispatch_async(dispatch_get_main_queue(),^
{
NSIndexPath *path = [NSIndexPath indexPathForRow:subIdx inSection:idx];
[self.albumsTableView deleteRowsAtIndexPaths:#[path] withRowAnimation:UITableViewRowAnimationNone];
// Confirmed data is updating
NSLog(#"%#",[self sectionIndexTitlesForTableView:self.albumsTableView]);
// Does nothing
[self.albumsTableView setNeedsDisplay];
});
}
}
Try this function
- reloadSectionIndexTitles
This method gives you a way to update the section index after inserting or deleting sections without having to reload the whole table.
Related
I have 3 or 2 sections (depending on datasource), in my grouped UITableView. I am trying to reload the last section via:
dispatch_async(dispatch_get_main_queue(), ^{
[UIView performWithoutAnimation:^{
[feedDetailTB reloadSections:[NSIndexSet indexSetWithIndex:feedDetailTB.numberOfSections-1] withRowAnimation:UITableViewRowAnimationNone];
}];
});
First of all, the footer never disappears. The data source basically keeps track of whether there are more comments or not (a simple load more functionality). In the viewForFooterInSection I simply return nil, when all the comments have been loaded.
But, as you see in the GIF, at first the loading button stays there. It is even accessible and works. When I scroll up, it vanishes and one can see it in the bottom, which is correct. But after all the comments have been reloaded, it should vanish, but sadly it stays there.
If I use reloadData it works fine. But I can't used it, since I have other sections, which I don't need to reload.
Second, there is a weird animation/flickering of the row items, even when I have used UITableViewRowAnimationNone. Not visible in the GIF
You should implement "isTheLastSection" according to your logic
- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
if (isTheLastSection) {
return 40;
}
return 0;
}
In order to add new rows to a section, you must use the insertRowsAtIndexPaths rather than just adding new objects to data source and reloading a section.
Here's the code:
NSMutableArray *newCommentsIndexPath = [[NSMutableArray alloc] init];
for (NSInteger i = currentCount; i < (_postDetailDatasource.commentsFeedInfo.allCommentsArray.count + serverComments.count); i ++)
{
NSIndexPath *idxPath = [NSIndexPath indexPathForRow:i inSection:sectionNumber];
[newCommentsIndexPath addObject:idxPath];
}
[_postDetailDatasource.commentsFeedInfo.allCommentsArray addObjectsFromArray:serverComments];
[feedDetailTB beginUpdates];
[feedDetailTB insertRowsAtIndexPaths:newCommentsIndexPath withRowAnimation:UITableViewRowAnimationFade];
[feedDetailTB endUpdates];
I don't know how to figure out whether I get to the last IndexPath and when to "rewind" and scroll to the first IndexPath
This is some setup:
- (void)viewWillLayoutSubviews;
{
[super viewWillLayoutSubviews];
UICollectionViewFlowLayout *flowLayout = (id)self.collectionView.collectionViewLayout;
if (UIDeviceOrientationIsLandscape([[UIApplication sharedApplication] statusBarOrientation])) {
flowLayout.itemSize = CGSizeMake(1024.0f, 768.0f);
} else {
flowLayout.itemSize = CGSizeMake(1024.0f, 768.0f);
}
[flowLayout invalidateLayout]; //force the elements to get laid out again with the new size
visibleItems = [self.collectionView indexPathsForVisibleItems];
self.currentIndexPath = [visibleItems firstObject];
[self.collectionView.collectionViewLayout invalidateLayout];
}
This is my button code:
- (IBAction)addToUploadQueque:(id)sender {
NSLog(#"current: %#",self.currentIndexPath);
NSInteger section = [self numberOfSectionsInCollectionView:self.collectionView] - 1;
NSInteger item = [self collectionView:self.collectionView numberOfItemsInSection:section]-1;
NSIndexPath *lastIndexPath = [NSIndexPath indexPathForItem:item inSection:section];
NSIndexPath *firstIndexpath =[NSIndexPath indexPathForItem:0 inSection:0];
NSLog(#"current: %#",lastIndexPath);
if (self.currentIndexPath <= lastIndexPath) {
NSInteger newLast = [self.currentIndexPath indexAtPosition:self.currentIndexPath.length-1]+1;
self.currentIndexPath = [[self.currentIndexPath indexPathByRemovingLastIndex] indexPathByAddingIndex:newLast];
[self.collectionView scrollToItemAtIndexPath:self.currentIndexPath
atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally
animated:YES];
}else{
self.currentIndexPath = [visibleItems firstObject];
[self.collectionView scrollToItemAtIndexPath:self.currentIndexPath
atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally
animated:YES];
}
}
I'm making a button that iterates through each cell in the collection view and when it gets to the end (instead of going out of bounds) scroll back to the first cell.
Can anyone tell me what i'm doing wrong?
Judging from your comments, it doesn't sound like you want to just enumerate the visible cells in one pass, but rather want to enumerate through them manually. And it sounds like you're having an issue getting the next NSIndexPath. The problem with your code snippet is that you're incrementing the row/item (depending upon whether you're dealing with UITableView or UICollectionView), but not considering whether you've reached the end of a section, much less the end of the data source, before you try to use your incremented data source.
You could do something like:
NSInteger item = self.currentIndexPath.item;
NSInteger section = self.currentIndexPath.section;
item++; // go to next item
if (item >= [self.collectionView numberOfItemsInSection:section]) { // if you reached end of section ...
item = 0; // ... go to the start of the next section
section++;
if (section >= [self.collectionView numberOfSections]) { // if you reached the end of the data source ...
// all done, so set section to zero to go back to beginning, e.g. // ... then you're done
section = 0;
}
}
self.currentIndexPath = [NSIndexPath indexPathForItem:item inSection:section]; // otherwise, this is your new NSIndexPath
BTW, if we're going to focus on your code snippet, the another issue is that you're using the <= operator to compare two index paths. You cannot do that. You have to use the compare method of NSIndexPath.
But that if statement strikes me as unnecessary, as there is no index path in the data source after the last index path. If you're incrementing logic (above) correctly detects the end of the data source, then this if statement is unnecessary.
There are many, many issues in this code. But I'm wondering whether, rather than going through all of those details, whether a simpler approach is possible. If you just want to perform uploads for all of the visible rows, perhaps you could do something radically simpler, such as:
for (NSIndexPath *indexPath in self.collectionView.indexPathsForVisibleItems) {
// if the cell has some visual indication to reflect upload has been initiated,
// do that here
// do your asynchronous upload here, where the completion block dispatches
// updates to the cell/collectionView (to reflect that the individual upload
// is done)
}
Note, your code is scrolling to the cell (presumably when the upload is done). I might try to dissuade you from that approach, but instead just update the cell (e.g. set some flag that your cellForItemAtIndexPath method references, and then call reloadItemsAtIndexPaths for each row as that row finishes. Because uploads can be slow, you might not want the UI scrolling around as these asynchronous uploads finish.
I have spent hours searching for the solution with out any luck. I am trying to delete a row (also deselect same row) programmatically. After row deletion call below, UITableViewDelgate methods get called expectedly and data source is updated but UITableView is not refreshed. deselectRowAtIndexPath call also does not work. I tried all kinds of scenarios as shown by commented lines.
Here is my code:
checkoutPerson is called as a result of observer listening for NSNotificationCenter messages.
- (void) checkoutPerson: (NSNumber*) personId {
Person *person = [_people objectForKey:personId];
if( person )
{
// Remove person from data source
int rowIndex = person.rowIndex;
S2Log(#"Deleting row number=%d", rowIndex);
[_allKeys removeObjectAtIndex:rowIndex];
[_people removeObjectForKey: personId];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:rowIndex inSection:0];
//[[self tableView] beginUpdates];
[self.tableView deselectRowAtIndexPath:indexPath animated:YES];
S2Log(#"Deleting indexPath row=%d", [indexPath row]);
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
//[[self tableView] endUpdates];
S2Log(#"Reloading data");
//[[self tableView] reloadData];
//[self performSelector:#selector(refreshView) withObject:nil afterDelay:1.5];
//[self.tableView performSelectorOnMainThread:#selector(reloadData) withObject:nil waitUntilDone:YES];
}
}
I will appreciate for help.
Thanks
-Virendra
I believe deleted cell is not being recycled. If I delete row in the middle, last row is always erased (since there is one less item) but the deleted row remains.
Use the above code between two function for table view
[tableView beginUpdates];
// the deletion code from data source and UITableView
[tableView endUpdates];
By calling this functions you are telling UITableView that you are about to make updates for deleting your cell.
Edit
The other problem I see with your code is you first delete the data from the data source.
Now you are asking for the UITableViewCell (which actually reloads the UITableView)
and then you are deleting the row from UITableView
I guess you should fetch the UITableViewCell before deleting values from your data source.
I found the problem. It has nothing to do with the code I posted above. It is syncing problem between visual display and the contents of data source. I have an embedded UITableView as part of a composite view. In composite view's controller, I was wiring up UITableView's delegate and data source to an instance of UITableViewController. Instead of this, I should have set UITableViewController's tableView property to the embedded UITableView. It seems that UITableView has to be contained within UITableViewController in order to correctly sync up table view visual display to the contents of data source. This also fixes row deselection and scrolling. I also needed to delay reloadData call in which case deleteRowsAtIndexPaths:withRowAnimation is not required. All you need is to modify the contents of your data source and call reloadData with a delay of 1.5 Seconds.
Thanks to all for great help.
I have been struggling with this for a week and my head is about to explode.
Basically I use Prototype Cell, in CellWillAppear I did a little customizations like background color. Nothing fancy.
Due to this, my table view is always empty at start up (no cell) unless the array (data source) is filled with something. So what I did was in NumberOfRowsInSection:
return dataArray.count < 10? 10 : dataArray.count
I am doing this because I would like to see at least some empty cells when there is no data.
Meaning it will show on start up at least 10 empty cells.
To add data to the cell, I call the delegate method in my tableviewcontroller each and every time to add one single entity in the data array (am doing this, because I think it would be faster than waiting until the whole array is filled then call [self.tableView reloadData];) and then refresh it by using reloadRowsAtIndexPaths. But it crashed every single time when it reached to index 10 (error: ... before update number of data was 10, but after update is 11).
What I really want is:
1.) prepare some data
2.) send it to uitableview controller and add it to an array there, instead of waiting and then sending a whole array to table view and refresh at once.
3.) reload just one row after the update (instead of using reloadData -> since I have different color of cell, the whole reload thing cause my table view flash madly).
The one thing I am doing to cell customization is in willDisplayCell:
What I did there is to change the background color of the cell. Again, nothing fancy.
But since there is no data at start up, no cell is ever visible (ui tablew with no cell at displayed at all), unless I did this
return dataArray.count < 10? 10 : dataArray.count;
just so there are at least 10 empty cells showing (WHY do I have to do the above just to display some customized empty cells beats me...).
Using reloadData is to refresh no problem, but since I am updating the data source array in table view every time data is ready instead of saving all prepared data to this array and send it over to table view to update by using reloadData, I would like to update row by row.
I kind of feel that the error comes from the fact that, if I add one item in the array and then call reloadRowsAtIndexPath, it will say "Ok, you had one item before, but after update there is 2! Inconsistency.."
I have already tried using [tableView beginUpdate]; and [tableView endUpdate];
Nothing has worked so far.....
So to sum up: how can I have different colors of cells showing even when the data array is empty on start up (just like the default ui table view with cells displaying completely even with no data) and update just one of the cells once a piece of data is ready instead of updating the whole ui table view with reloadData?
Many thanks in advance, please advise. Regards.
"how can I have different colors of cells showing even when the data array is empty"
Don't have an empty array, have a mutable array where all the members are initially empty strings, and replace those with your real data when you get it.
"update just one of the cells once a piece of data is ready"
Update your array with the new data, and then use reloadRowsAtIndexPaths:withRowAnimation: to update the table. If you want to see the table update row by row (slow enough to see), then put your data in a temporary array first, then add it one element at a time using performSelector:withObject:afterDelay:, calling reloadRowsAtIndexPaths:withRowAnimation: after each addition.
It's a little hard to tell exactly what you want, but here is an example of what I mean. This table displays 20 empty rows, all with different colors, for 2 seconds, then it replaces the empty strings in displayData with the strings in theData one by one at a rate of 10 per second.
#interface TableController ()
#property (strong,nonatomic) NSArray *theData;
#property (strong,nonatomic) NSMutableArray *displayData;
#end
#implementation TableController
- (void)viewDidLoad {
[super viewDidLoad];
self.displayData = [#[#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#"",#""] mutableCopy];
self.theData = #[#"One",#"Two",#"Three",#"Four",#"Five",#"Six",#"Seven",#"Eight",#"Nine",#"ten",#"Black",#"Brown",#"Red",#"Orange",#"Yellow",#"Green",#"Blue",#"Violet",#"Gray",#"White"];
[self.tableView reloadData];
[self performSelector:#selector(addData) withObject:nil afterDelay:2];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return self.displayData.count;
}
-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
UIColor *cellTint = [UIColor colorWithHue:indexPath.row * .05 saturation:1.0 brightness:1.0 alpha:1.0];
cell.backgroundColor = cellTint;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
cell.textLabel.text = self.displayData[indexPath.row];
return cell;
}
-(void)addData {
static int i = 0;
[self.displayData replaceObjectAtIndex:i withObject:self.theData[i]];
[self.tableView reloadRowsAtIndexPaths:#[[NSIndexPath indexPathForRow:i inSection:0]] withRowAnimation:UITableViewRowAnimationNone];
i++;
if (i < self.displayData.count) [self performSelector:#selector(addData) withObject:nil afterDelay:.1];
}
If you don't want any delay between row updates, and you want to make it work when displayArray has a different number of rows that theData, this version of addData should work:
-(void)addData {
static int i = 0;
if (i < self.displayData.count && i< self.theData.count) {
[self.displayData replaceObjectAtIndex:i withObject:self.theData[i]];
[self.tableView reloadRowsAtIndexPaths:#[[NSIndexPath indexPathForRow:i inSection:0]] withRowAnimation:UITableViewRowAnimationNone];
i++;
[self addData];
}else if (i >= self.displayData.count && i< self.theData.count) {
[self.displayData addObject:self.theData[i]];
[self.tableView insertRowsAtIndexPaths:#[[NSIndexPath indexPathForRow:i inSection:0]] withRowAnimation:UITableViewRowAnimationNone];
i++;
[self addData];
}
}
I am trying to implement a view similar to that of Apple's calendar application's setting the start time and end time view. I have the view looking great, but I am running into two problems. First, I want to have the first row selected automatically. I sort of have this working using:
NSIndexPath *indexPath=[NSIndexPath indexPathForRow:0 inSection:0];
[dateTableView selectRowAtIndexPath:indexPath animated:YES scrollPosition:UITableViewScrollPositionBottom];
However, an animation shows, visually selecting the rown when the view is loaded, I want it to already be selected when the view loads.
The second, and much more important, problem is that when I reload the data after the picker has updated I lose the selection, and my task simply doesn't work.
Now I know this is the default action of reloadData, I am looking for an alternative method to accomplish my goal, or perhaps how I can augment reloadData to not deselect the current selection.
My task is included below:
-(IBAction)dateChanged
{
NSIndexPath *index = self.dateTableView.indexPathForSelectedRow;
if(index == 0)
{
if (self.date2 == plusOne ) {
self.date = [datePicker date];
plusOne = [self.date dateByAddingTimeInterval:60*60];
self.date2 = plusOne;
}
else
{
self.date = [datePicker date];
}
}
else{
self.date2 = [datePicker date];
}
[dateTableView reloadData];
}
Note: plusOne is a variable that initially indicates an hour from the current time.
Thanks in advance!
For the first problem, set animated:NO on the method call. You are currently setting it to YES.
[dateTableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionBottom];
For the second problem, it's not really clear what you are trying to select after reloading the data, but I see a problem with this line:
if(index == 0)
You are asking if the pointer to the object is 0. I think what you want is either to check that index == nil or that index.section == 0 && index.row == 0 or something like that.
Anyway, if you call reloadData on the UITableView, you're going to lose the selection. At that point, you need to select a new row. If there is an item in your data model that you want to select, you need to figure out where it is and select it based on where it will be in the table (You should know this because you are providing that information in the UITableViewDataSource delegate methods.). Alternatively, if you want to select the NSIndexPath you saved in the first line of dateChanged, just select it after reloading the data.
For the first problem, write your code in didSelectRowAtIndexPath: in a method. You can then call this method from didSelectRowAtIndexPath: You should pass indexPath as argument to your function like,
-(void)doActionsInDidSelectRow:(NSIndexPath*)indexPath{
// write code.
}
In viewDidLoad call this method as
-(void)viewDidLoad{
NSIndexPath *indexPath=[NSIndexPath indexPathForRow:0 inSection:0];
[dateTableView selectRowAtIndexPath:indexPath animated:YES scrollPosition:UITableViewScrollPositionBottom];
[self doActionsInDidSelectRow:indexPath];
}
For the second problem my suggestion is, each time when you selecting a cell store that cell's text in a NSString. When you reload data, inside cellForRowAtIndexPath: just compare cell's text with the string content you stored previously. If they equal just make selection using
[dateTableView selectRowAtIndexPath:indexPath animated:YES scrollPosition:UITableViewScrollPositionBottom];
method. Hope this will solve your issues.