rac_signalForSelector fromProtocol, selector does not exist

Question

I'm trying to wrap WKWebViewDelegate using Reactive Cocoa.

class WebContainerView: UIView, WKNavigationDelegate
{
let webView:WKWebView

required init(coder aDecoder: NSCoder){
    webView = WKWebView(frame: CGRect())
    super.init(coder: aDecoder)
    self.addSubview(webView)

    let proto = WKNavigationDelegate.self
    let selector:Selector = "webView(_:decidePolicyForNavigationAction:decisionHandler:)"
    let signal =   webView.rac_signalForSelector(selector, fromProtocol: proto).subscribeNext( { _ in
        println("Test")
    })
    webView.navigationDelegate = self
}}

However I get this error upon creating the signal

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Selector webView(_:decidePolicyForNavigationAction:decisionHandler:) does not exist in <WKNavigationDelegate>'

The selector name is exactly the output calling this in the delegate method:

NSLog(%@, "__FUNCTION__")

Answer 1

I figured out the solution to this error, which was changing this line:

let selector:Selector = "webView(_:decidePolicyForNavigationAction:decisionHandler:)"

to this:

let selector:Selector = "webView:decidePolicyForNavigationAction:decisionHandler:"