decidePolicyFor delegate method:
import WebKit
@objc extension DocumentationVC
{
func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void)
Being called just alright in swift 5 minimal concurrency.
Raising concurrency to complete with swift 5 or swift 6. Changing the code to avoid warnings:
@preconcurrency import WebKit
@objc extension DocumentationVC
{
func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping (WKNavigationActionPolicy) -> Void) {
The delegate method is not being called. Changing back to swift 5 concurrency minimal - it is called.
Looking at WKNavigationDelegate:
WK_SWIFT_UI_ACTOR
@protocol WKNavigationDelegate <NSObject>
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(WK_SWIFT_UI_ACTOR void (^)(WKNavigationActionPolicy))decisionHandler WK_SWIFT_ASYNC(3);
Changing the delegate method to:
func webView(_ webView: WKWebView, decidePolicyFor navigationAction: WKNavigationAction, decisionHandler: @escaping @MainActor (WKNavigationActionPolicy) -> Void) {
And it is called across swift 5 concurrency minimal to complete to swift 6.
I thought, the meaning of @preconcurrency import WebKit
was to keep the delegate without @MainActor before the (WKNavigationActionPolicy) still matching regardless the swift concurrency mode?
My point is - this can introduce hidden breaking changes? I didn't see this documented anyhow at: https://www.swift.org/migration/documentation/migrationguide/.
decidePolicyFor is an optional method - so if signature 'mismatches' - there will be no warning on not-implementing the delegate method.
How do we catch or diagnose irregularities like this? Is it something @preconcurrency import WebKit
should be ensuring and it is not?
Is this delegate mismatch a bug on swift side or something we should be taking care of while migrating? If it is on us, how do we diagnose these potential mismatches?