UITableView reload section - iphone

Question

I want to reload only one section not the full table. Is there any method in UITableView.
[tableView reloadData] is used to load full table.
I want to know how to load only one section, as I have large number of rows in the table.

Answer 1

The reloadSections method bugs me -- as I have to construct a few objects. This is great if you need the flexibility, but sometimes I also just want the simplicity too. It goes like this:
NSRange range = NSMakeRange(0, 1);
NSIndexSet *section = [NSIndexSet indexSetWithIndexesInRange:range];
[self.tableView reloadSections:section withRowAnimation:UITableViewRowAnimationNone];
This will reload the first section. I prefer to have a category on UITableView and just call this method:
[self.tableView reloadSectionDU:0 withRowAnimation:UITableViewRowAnimationNone];
My category method looks like this:
#implementation UITableView (DUExtensions)
- (void) reloadSectionDU:(NSInteger)section withRowAnimation:(UITableViewRowAnimation)rowAnimation {
NSRange range = NSMakeRange(section, 1);
NSIndexSet *sectionToReload = [NSIndexSet indexSetWithIndexesInRange:range];
[self reloadSections:sectionToReload withRowAnimation:rowAnimation];
}

Answer 2

Yes, there is:
- (void)reloadSections:(NSIndexSet *)sections withRowAnimation:(UITableViewRowAnimation)animation

Answer 3

But you can reload only sections which contain same number of rows (or you have to manually add or remove them). Otherwise you will get:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 2. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (0), plus or minus the number of rows inserted or deleted from that section (0 inserted, 0 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'
Which is not required when you use [tableView reloadData].
When you need to reload a section and you have changed number of rows inside it, you could use something like this:
NSIndexSet *indexSet = [NSIndexSet indexSetWithIndex:section];
[self beginUpdates];
[self deleteSections:indexSet withRowAnimation:rowAnimation];
[self insertSections:indexSet withRowAnimation:rowAnimation];
[self endUpdates];
If you put it in a category (like bandejapaisa shows) it could look like this:
- (void)reloadSection:(NSInteger)section withRowAnimation:(UITableViewRowAnimation)rowAnimation {
NSIndexSet *indexSet = [NSIndexSet indexSetWithIndex:section];
[self beginUpdates];
[self deleteSections:indexSet withRowAnimation:rowAnimation];
[self insertSections:indexSet withRowAnimation:rowAnimation];
[self endUpdates];
}

Answer 4

For Swift 3, 4 and 5
let sectionToReload = 1
let indexSet: IndexSet = [sectionToReload]
self.tableView.reloadSections(indexSet, with: .automatic)

Answer 5

that the correct way:
[self.tableView beginUpdates];
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationNone];
[self.tableView endUpdates];

Answer 6

Based on the accepted answer here, I made a function that will reload all sections in the table using an animation. This could probably be optimized by reloading only visible sections.
[self.tableView reloadData];
NSRange range = NSMakeRange(0, [self numberOfSectionsInTableView:self.tableView]);
NSIndexSet *sections = [NSIndexSet indexSetWithIndexesInRange:range];
[self.tableView reloadSections:sections withRowAnimation:UITableViewRowAnimationFade];
In my case, I had to force a reloadData before the section animation, because the underlying data for the table had changed. It animates properly however.

Answer 7

You need this... For Reload Row
- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation
or For Reload section
- (void)reloadSections:(NSIndexSet *)sections withRowAnimation:(UITableViewRowAnimation)animation

Answer 8

Here is the method, you can pass section details in different ways
[self.tableView reloadSections:[[NSIndexSet alloc] initWithIndex:1] withRowAnimation:NO];
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:1] withRowAnimation:UITableViewRowAnimationNone];
Reloading particular sections improves performance for the table view as well some time it also avoid some issues like floating/moving custom headers-footers in your view. SO try to use reloadSection than relaodData whenever possible

Answer 9

Try to use
[self.tableView beginUpdates];
[self.tableView endUpdates];
Hope this will solve your issue.

Answer 10

But you can reload only sections which contain same number of rows (or you have to manually add or remove them). Otherwise you will get an NSInternalInconsistencyException.
Steps:
calculate which rows to remove and/or insert
generate an IndexPath array from these
call related tableView methods
now you can safely call reloadSections :) Reload section will call update for the rest of the indexes.
Or you can use a library like : https://github.com/onmyway133/DeepDiff
Swift pseodo code:
tableView.deleteRows(at: valueIndexesToRemove, with: .automatic)
tableView.insertRows(at: valueIndexesToInsert, with: .automatic)
tableView.reloadSections(IndexSet([section]), with: .automatic)

Answer 11

If you have custom section view you can add a weak reference to it in your view controller and update it whenever you want. Here is my code for reference:
#property (weak, nonatomic) UILabel *tableHeaderLabel;
....
-(UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
UITableViewHeaderFooterView *myHeader = [[UITableViewHeaderFooterView alloc] init];
UILabel *titleLabel = [[UILabel alloc] init];
[titleLabel setFrame:CGRectMake(20, 0, 280, 20)];
[titleLabel setTextAlignment:NSTextAlignmentRight];
[titleLabel setBackgroundColor:[UIColor clearColor]];
[titleLabel setFont:[UIFont systemFontOfSize:12]];
[myHeader addSubview:titleLabel];
self.tableHeaderLabel = titleLabel; //save reference so we can update the header later
return myHeader;
}
Then later on you can update your section like this:
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
self.tableHeaderLabel.text = [NSString stringWithFormat:#"Showing row: %ld", indexPath.row];
}