[ACCEPTED]-Is it possible to add observer to tableView.contentOffset?-observer-pattern

Accepted answer

Score: 24

UITableView is a UIScrollView subclass so you can use the UIScrollViewDelegate method 3 scrollViewDidScroll: to be notified when the view scrolled. Check 2 the contentOffset of the scrollView in that method

contentOffset is a key path, so 1 you can also observe its changes using KVO

[self.tableView addObserver:self forKeyPath:@"contentOffset" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:nil];

Score: 13

Swift 5

tableContentObserver = table.observe(\UITableView.contentOffset, options: .new) { [weak self] table, change in
    self?.navigationItem.rightBarButtonItem?.title = "\(change.newValue)"
}

Score: 4

Swift 3

Add an observer for the contentOffset key path using 2 Key-Value Observing (KVO):

tableView.addObserver(self, forKeyPath: #keyPath(UIScrollView.contentOffset), options: [.old, .new], context: nil)

And handle notifications 1 for changes:

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == #keyPath(UIScrollView.contentOffset) {
      // Your code
    }
  }

Source: stackoverflow.com

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