Understanding decidePolicyForNavigationResponse with user interaction - objective-c

Question

I would like to get user approval before opening a link using WKWebView. (Objective C) I am using decidePolicyForNaviagationResponse.
When it encounters a link in the HTML it should ask using a UIAlertController if it is OK to follow the link or not (in the simplest implementation).
However it appears to be running asynchronously, so first it opens the link and then eventually gets around to popping up the alert.
How do I encounter the link, pop up the alert and THEN either open the link or not. I’m guessing either something about blocks that I don’t understand like a completion handler or perhaps using semaphores, although my modest attempts at them didn’t work.
I have simplified the code to make it clear what’s happening.
Thank you!
static bool launchPermission = false;
#property (strong, nonatomic) WKWebViewConfiguration *theConfiguration;
#property (strong, nonatomic) WKWebView *webView;
.
.
.
_webView.navigationDelegate = self;
[_webView loadRequest:nsrequest];
[self.view addSubview:_webView];
.
.
.
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{
[self askPermissionForExternalLink];
if (launchPermission)
{
decisionHandler(WKNavigationResponsePolicyAllow);
}
else
{
decisionHandler(WKNavigationResponsePolicyCancel);
}
}
- (void) askPermissionForExternalLink
{
UIAlertController *alert = [UIAlertController alertControllerWithTitle:#"Open external Web Conten?" message:#"Link is embedded with other content" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *cancelAction = [UIAlertAction
actionWithTitle:NSLocalizedString(#"Cancel", #"Cancel action")
style:UIAlertActionStyleCancel
handler:^(UIAlertAction *action)
{
NSLog(#"Cancel action");
[self cancelMethod];
//return;
}];
UIAlertAction *okAction = [UIAlertAction
actionWithTitle:NSLocalizedString(#"OK", #"OK action")
style:UIAlertActionStyleDefault
handler:^(UIAlertAction *action)
{
NSLog(#"OK action");
//[self launchURL];
[self OKMethod];
}];
[alert addAction:cancelAction];
[alert addAction:okAction];
[alert show];
}
- (bool) cancelMethod
{
launchPermission = false;
return false;
}
- (bool) OKMethod
{
launchPermission = true;
return true;
}

Answer 1

You can try it in this way using blocks first in decidePolicyForNavigationResponse make decideAction inside the block
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{
void (^ launchPermission)(BOOL) = ^(BOOL isAllow)
{
if(isAllow)
{
decisionHandler(WKNavigationActionPolicyAllow);
}
else
{
decisionHandler(WKNavigationActionPolicyCancel);
}
return;
};
[self askPermissionForExternalLink];
}
here based on user choice send YES or NO to launchPermission block
- (void) askPermissionForExternalLink
{
UIAlertController *alert = [UIAlertController alertControllerWithTitle:#"Open external Web Conten?" message:#"Link is embedded with other content" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *cancelAction = [UIAlertAction
actionWithTitle:NSLocalizedString(#"Cancel", #"Cancel action")
style:UIAlertActionStyleCancel
handler:^(UIAlertAction *action)
{
NSLog(#"Cancel action");
launchPermission(NO);
return;
}];
UIAlertAction *okAction = [UIAlertAction
actionWithTitle:NSLocalizedString(#"OK", #"OK action")
style:UIAlertActionStyleDefault
handler:^(UIAlertAction *action)
{
NSLog(#"OK action");
launchPermission(YES);
return ;
}];
[alert addAction:cancelAction];
[alert addAction:okAction];
[alert show];
}