   <p class="aside-title">Swift</p>
                          <pre class="highlight swift"><code><span class="kd">func</span> <span class="nf">add</span><span class="p">(</span><span class="nv">routingObserver</span><span class="p">:</span> <span class="kt">RoutingObserver</span><span class="p">,</span> <span class="nv">priority</span><span class="p">:</span> <span class="kt">Int</span><span class="p">,</span> <span class="nv">routePattern</span><span class="p">:</span> <span class="kt">String</span><span c