Find a subview that satisfies a predicate recursively

subviews.swift

extension UIView {
    
    /// Traverses subviews recursively with breadth first search, returns the first subview that
    /// satisfies the predicate.
    func firstSubview(where predicate: (UIView) -> Bool) -> UIView? {
        var subviewsToTraverse = subviews

        while subviewsToTraverse.count > 0 {
            guard !predicate(subviewsToTraverse[0]) else {
                return subviewsToTraverse[0]
            }
            subviewsToTraverse.append(contentsOf: subviewsToTraverse[0].subviews)
            subviewsToTraverse.remove(at: 0)
        }

        return nil
    }   
}