Fix custom instance domains not being parsed correctly

Tusker/Screens/Onboarding/InstanceSelectorTableViewController.swift

@@ -74,12 +74,36 @@ class InstanceSelectorTableViewController: UITableViewController {
         loadRecommendedInstances()
     }
     
-    private func updateSpecificInstance(domain: String) {
+    private func parseURLComponents(input: String) -> URLComponents {
-        var components = URLComponents(string: domain)!
+        // we can't just use the URLComponents(string:) initializer, because when given just a domain (w/o protocol), it interprets it as the path
+        var input = input
+        var components = URLComponents()
+        // extract protocol
+        if input.contains("://") {
+            let parts = input.components(separatedBy: "://")
+            components.scheme = parts.first!
+            input = parts.last!
+        }
         if components.scheme != "https" && components.scheme != "http" {
             components.scheme = "https"
         }
-        components.path = "/"
+        // drop path
+        if input.contains("/") {
+            let parts = input.components(separatedBy: "/")
+            input = parts.first!
+        }
+        // parse port
+        if input.contains(":") {
+            let parts = input.components(separatedBy: ":")
+            input = parts.first!
+            components.port = Int(parts.last!)
+        }
+        components.host = input
+        return components
+    }
+    
+    private func updateSpecificInstance(domain: String) {
+        let components = parseURLComponents(input: domain)
 
         let client = Client(baseURL: components.url!)
         let request = client.getInstance()