A UIRefreshControl subclass that you can start animating before adding to the view hierarchy without worrying about broken animations and what not

RefreshControl.swift

import UIKit

/// A subclass that improves the usability of `UIRefreshControl` by:
///
/// 1. Providing the `isRefreshing` boolean binding.
/// 2. Deferring calls to `beginRefreshing()` until the time of appearance to avoid glitches.
/// 3. Automatically scrolling the parent scrollView to reveal the refresh control when scrolled to the top.
///
/// When using this subclass, you should not use ``beginRefreshing()`` or ``endRefreshing()`` and instead set the ``isRefreshing`` property to show and hide the refresh control.
///
/// You can call ``isRefreshing`` at any point after initialisation. If the control is not yet in the view hierarchy, the underlying call to ``beginRefreshing()`` will be deferred until the correct time.
class RefreshControl: UIRefreshControl {
    private var shouldBeginRefreshingOnAppear = false

    /// Indicates if the control is currently showing the refresh animation, or if it will show the animation once the receiver appears on screen.
    ///
    /// Set this property to show or hide the refresh control.
    override var isRefreshing: Bool {
        get {
            shouldBeginRefreshingOnAppear || super.isRefreshing
        }
        set {
            guard isRefreshing != newValue else { return }

            if newValue && window == nil {
                shouldBeginRefreshingOnAppear = true
            } else if !newValue && shouldBeginRefreshingOnAppear {
                shouldBeginRefreshingOnAppear = false
            }

            if newValue && !shouldBeginRefreshingOnAppear && !super.isRefreshing {
                beginRefreshingAndRevealIfNeeded(true)
            } else if !newValue && super.isRefreshing {
                super.endRefreshing()
            }
        }
    }

    override func didMoveToWindow() {
        super.didMoveToWindow()

        if window != nil && shouldBeginRefreshingOnAppear && !super.isRefreshing {
            shouldBeginRefreshingOnAppear = false

            UIView.animate(withDuration: 0, animations: { }, completion: { _ in
                self.beginRefreshingAndRevealIfNeeded(false)
            })
        }
    }

    private func beginRefreshingAndRevealIfNeeded(_ animated: Bool) {
        let wasAtTop = if let scrollView = superview as? UIScrollView {
            scrollView.contentOffset.y == -scrollView.adjustedContentInset.top
        } else {
            false
        }

        super.beginRefreshing()

        if wasAtTop, let scrollView = superview as? UIScrollView {
            scrollView.setContentOffset(
                CGPoint(x: scrollView.contentOffset.x, y: -scrollView.adjustedContentInset.top),
                animated: animated
            )
        }
    }

    @available(*, unavailable, message: "Use the `isRefreshing` property instead")
    override func beginRefreshing() {
        super.beginRefreshing()
    }

    @available(*, unavailable, message: "Use the `isRefreshing` property instead")
    override func endRefreshing() {
        super.endRefreshing()
    }
}