Swift UITableView自动高度

Question

I have a design, where UITableView is in UIScrollView with other content and the content is scrolling with the table data. It means, that table has scrolling disabled and is stretched to full size.

I'm using autolayout and the table has height constraint, set to some default value.

Then I have overwritten viewWillLayoutSubviews method:

override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()
    if (self.itemTableView.contentSize.height > 0) {
        self.itemTableViewHeightConstraint.constant = self.itemTableView.contentSize.height
    }
}

With this method in place, when I called self.itemTableView.reloadData() after loading the data from the REST, the height constraint was set to table content height, which was great.

This used to work for me in many projects, but for some reason it is not working in the latest one, written in swift 4. Does something changed? Why tableView reloadData() method does not invoke viewWillLayoutSubviews()?

Answer 1

问题是tableView（_ tableView：UITableView，cellForRowAt indexPath：IndexPath）在返回行之前未调用self.view.setNeedsLayout（）。