title: Call Swift func from Objective-C with parameter
body: <p>I want to integrate a Swift class into an UIViewController class.
  I think I made all settings correct. I have a class rURLTask:NSObject with a function:</p>
  
  <pre><code>@objc public func primer() {
      print("primer")
  }
  </code></pre>
  
  <p>In my .swift file and can call it from my Objective-C-class with:</p>
  
  <pre><code>[URLTask primer];
  </code></pre>
  
  <p>and it prints nicely.
  Another function is:</p>
  
  <pre><code>@objc public func ladeURL(url: URL?) {
      print("loadURL")
  }
  </code></pre>
  
  <p>but this one I cannot call from Objective-C. I try to write:</p>
  
  <pre><code>NSURL* testURL = [NSURL URLWithString:@"http://www.google.com"];    
  [URLTask ladeURL:testURL];
  </code></pre>
  
  <p>I get the error:</p>
  
  <blockquote>
    <p>No visible @interface for 'rURLTask' declares the selector 'ladeURL:'</p>
  </blockquote>
  
  <p>I think there is a very basic mistake. Using Objective-C in Swift 3 in another project worked well.</p>