Support NAME on WebViewDelegate trait impls

examples/browser/main.rs

@@ -91,7 +91,9 @@ impl Dispatcher for BasicApp {
 #[derive(Default)]
 pub struct WebViewInstance;
 
-impl WebViewDelegate for WebViewInstance {}
+impl WebViewDelegate for WebViewInstance {
+    const NAME: &'static str = "BrowserWebViewDelegate";
+}
 
 struct AppWindow {
     toolbar: Toolbar<BrowserToolbar>,

src/webview/class.rs

@@ -185,8 +185,8 @@ pub fn register_webview_class() -> *const Class {
 /// Registers an `NSViewController` that we effectively turn into a `WebViewController`. Acts as
 /// both a subclass of `NSViewController` and a delegate of the held `WKWebView` (for the various
 /// varieties of delegates needed there).
-pub fn register_webview_delegate_class<T: WebViewDelegate>() -> *const Class {
-    load_or_register_class("NSObject", "RSTWebViewDelegate", |decl| unsafe {
+pub fn register_webview_delegate_class<T: WebViewDelegate>(instance: &T) -> *const Class {
+    load_or_register_class("NSObject", instance.subclass_name(), |decl| unsafe {
         decl.add_ivar::<usize>(WEBVIEW_DELEGATE_PTR);
 
         // WKNavigationDelegate

src/webview/mod.rs

@@ -230,10 +230,11 @@ where
     /// Initializes a new WebView with a given `WebViewDelegate`. This enables you to respond to events
     /// and customize the view as a module, similar to class-based systems.
     pub fn with(config: WebViewConfig, delegate: T) -> WebView<T> {
+        let delegate_class = register_webview_delegate_class(&delegate);
         let mut delegate = Box::new(delegate);
 
         let objc_delegate = unsafe {
-            let objc_delegate: id = msg_send![register_webview_delegate_class::<T>(), new];
+            let objc_delegate: id = msg_send![delegate_class, new];
             let ptr: *const T = &*delegate;
             (&mut *objc_delegate).set_ivar(WEBVIEW_DELEGATE_PTR, ptr as usize);
             ShareId::from_ptr(objc_delegate)

src/webview/traits.rs

@@ -8,6 +8,17 @@ use crate::webview::WebView;
 
 /// You can implement this on structs to handle callbacks from the underlying `WKWebView`.
 pub trait WebViewDelegate {
+    /// Used to cache subclass creations on the Objective-C side.
+    /// You can just set this to be the name of your delegate type. This
+    /// value *must* be unique per-type.
+    const NAME: &'static str;
+
+    /// You should rarely (read: probably never) need to implement this yourself.
+    /// It simply acts as a getter for the associated `NAME` const on this trait.
+    fn subclass_name(&self) -> &'static str {
+        Self::NAME
+    }
+
     /// Called when the View is ready to work with. You're passed a `ViewHandle` - this is safe to
     /// store and use repeatedly, but it's not thread safe - any UI calls must be made from the
     /// main thread!