WKWebView Prompt

WKUIDelegate

To show prompt(alert, textinput, confirm), we need to implement WKUIDelegate and handle properly.

Implementation

Set delegate in your WKWebView

self.wkwebView.UIDelegate = self;

Implement WKUIDelegate

- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)())completionHandler {
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:webView.URL.host message:message preferredStyle:UIAlertControllerStyleAlert];
    
    [alertController addAction:[UIAlertAction actionWithTitle:NSLocalizedString(@"Close", nil) style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
        completionHandler();
    }]];
    [self presentViewController:alertController animated:YES completion:nil];
}

- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL))completionHandler {
    
    // TODO We have to think message to confirm "YES"
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:webView.URL.host message:message preferredStyle:UIAlertControllerStyleAlert];
    [alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        completionHandler(YES);
    }]];
    [alertController addAction:[UIAlertAction actionWithTitle:NSLocalizedString(@"Cancel", nil) style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
        completionHandler(NO);
    }]];
    [self presentViewController:alertController animated:YES completion:nil];
}

- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString *))completionHandler {
    
    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:prompt message:webView.URL.host preferredStyle:UIAlertControllerStyleAlert];
    [alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
        textField.text = defaultText;
    }];
    
    [alertController addAction:[UIAlertAction actionWithTitle:NSLocalizedString(@"OK", nil) style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        NSString *input = ((UITextField *)alertController.textFields.firstObject).text;
        completionHandler(input);
    }]];
    
    [alertController addAction:[UIAlertAction actionWithTitle:NSLocalizedString(@"Cancel", nil) style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
        completionHandler(nil);
    }]];
    [self presentViewController:alertController animated:YES completion:nil];
}

How to test

Access following page and check

Alert : TAG JavaScript alert
Confirm : TAG JavaScript prompt
Prompt : TAG JavaScript