While implementing infinite scrolling in Get Seated, I ran into a strange side-effect of calling endRefreshing() on a UIRefreshControl that isn’t animating: if the user is scrolling the view, any velocity from the user’s “flick” will be lost and the view will immediately stop scrolling.

It’s easy to hit this glitch if you call endRefreshing() every time new data finishes downloading from your server. Thankfully, UIRefreshControl has a property to detect if it’s currently refreshing. Just verify it returns true before you try to end refreshing.

Swift 3

if self.refreshControl?.isRefreshing == true {
    self.refreshControl?.endRefreshing()
}

Swift 2

if self.refreshControl?.refreshing == true {
    self.refreshControl?.endRefreshing()
}