Overriding non-@objc declarations from extensions is not supported : <p>Seemingly out of nowhere I started getting hundreds of errors associated with two extension functions that I use frequently.</p>

<p>I tried commenting out all the new code that preceding this error showing up. I also tried cleaning my build folder. How do I get ride of the error found in the title of this post? Why did it randomly appear when I've been using these extensions successfully for months?</p>

<pre><code>extension UITableViewCell {

public func getSize(large: CGFloat, medium: CGFloat, small: CGFloat) -&gt; CGFloat {
    var size = CGFloat()
    let screenHeight = Int(UIScreen.main.bounds.height)
    if screenHeight &gt;= 800 {
        size = large
    } else if screenHeight &gt;= 600 {
        size = medium
    } else {
        size = small
    }
    return size
}

public func formatPrice(_ price: Int) -&gt; String {
    let lastDigit = price % 10
    var stringPrice = ""
    if lastDigit == 0 {
        stringPrice = "$\(Double(price) / 100)0"
    } else {
        stringPrice = "$\(Double(price) / 100)"
    }
    return stringPrice
}

}
</code></pre>
