How to Detect the End of Loading of Uitableview

How to detect the end of loading of UITableView

Improve to @RichX answer:
lastRow can be both [tableView numberOfRowsInSection: 0] - 1 or ((NSIndexPath*)[[tableView indexPathsForVisibleRows] lastObject]).row.
So the code will be:

-(void) tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if([indexPath row] == ((NSIndexPath*)[[tableView indexPathsForVisibleRows] lastObject]).row){
        //end of loading
        //for example [activityIndicator stopAnimating];
    }
}

UPDATE:
Well, @htafoya's comment is right. If you want this code to detect end of loading all data from source, it wouldn't, but that's not the original question. This code is for detecting when all cells that are meant to be visible are displayed. willDisplayCell: used here for smoother UI (single cell usually displays fast after willDisplay: call). You could also try it with tableView:didEndDisplayingCell:.

Can I call a function when UITableView has finished loading?

Try this delegate method, when this is called, the text is already in the cell, and you can test for it and add or remove the accessory. From the docs:

Discussion
A table view sends this message to its delegate just before it uses cell to draw a row, thereby permitting the delegate to customize the cell object before it is displayed. This method gives the delegate a chance to override state-based properties set earlier by the table view, such as selection and background color. After the delegate returns, the table view sets only the alpha and frame properties, and then only when animating rows as they slide in or out.

func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {

// check text and do something
}

How can I tell when UITableView has completed ReloadData?

The reload happens during the next layout pass, which normally happens when you return control to the run loop (after, say, your button action or whatever returns).

So one way to run something after the table view reloads is simply to force the table view to perform layout immediately:

[self.tableView reloadData];
[self.tableView layoutIfNeeded];
 NSIndexPath* indexPath = [NSIndexPath indexPathForRow: ([self.tableView numberOfRowsInSection:([self.tableView numberOfSections]-1)]-1) inSection: ([self.tableView numberOfSections]-1)];
[self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];

Another way is to schedule your after-layout code to run later using dispatch_async:

[self.tableView reloadData];

dispatch_async(dispatch_get_main_queue(), ^{
     NSIndexPath* indexPath = [NSIndexPath indexPathForRow: ([self.tableView numberOfRowsInSection:([self.tableView numberOfSections]-1)]-1) inSection:([self.tableView numberOfSections]-1)];

    [self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
});

UPDATE

Upon further investigation, I find that the table view sends tableView:numberOfSections: and tableView:numberOfRowsInSection: to its data source before returning from reloadData. If the delegate implements tableView:heightForRowAtIndexPath:, the table view also sends that (for each row) before returning from reloadData.

However, the table view does not send tableView:cellForRowAtIndexPath: or tableView:headerViewForSection until the layout phase, which happens by default when you return control to the run loop.

I also find that in a tiny test program, the code in your question properly scrolls to the bottom of the table view, without me doing anything special (like sending layoutIfNeeded or using dispatch_async).

Detect when UITableView has scrolled to the bottom

Swift 3

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    if indexPath.row + 1 == yourArray.count {
        print("do something")
    }
}

Detect when UITableViewCell did load

There are two different ways you could do it.

In your UITableViewDelegate you can implement the delegate method that is called when a cell is about to be displayed.

func tableView(_ tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
    // Update the cell
}

Or in your UITableViewCell subclass you could implement didMoveToSuperView.

override func didMoveToSuperview() {
    super.didMoveToSuperview()
    if superview != nil {
        // Update the cell
    }
}

---

Related Topics