ionic ios issue white page when doing REST Calls - ios

Question

I've got an ionic react app which fetches data from a rest API. When I bundle the ab with ionic server or on Android the app works fine.
When I run the same code on iOS I got a blank page. Some Versions before it worked on iOS as well. When I rebase my code the version 5 days ago now it doesn't work at all.
the code looks like this:
export default function PostsContainer() {
let {categoryid} = useParams<any>();
const [posts, setPosts] = useState<any[]>([]);
const [page, setPage] = useState<number>(1);
const [totPages, setTotPages] = useState<number>(1);
const [title, setTitle] = useState<string>("Recent posts");
const baseUrl = BASE_URL + "wp-json/wp/v2";
const [loadingPosts, setLoadingPosts] = useState<boolean>(false);
useEffect(() => {
async function loadPosts() {
setLoadingPosts(false)
let url = baseUrl + "/posts?status=publish&page=" + page;
if (categoryid !== undefined) {
url = url + "&categories=" + categoryid;
getCategoryName(categoryid);
}
const response = await fetch(url);
if (!response.ok) {
return;
}
const totalPages = await response.headers.get("x-wp-totalpages");
const postsTemp = await response.json();
setPosts(postsTemp);
setTotPages(Number(totalPages));
setLoadingPosts(true);
console.log(posts)
}
loadPosts();
}, [page, categoryid]);
function handleClickNextPage() {
setPage(page + 1);
}
async function getCategoryName(id: number) {
let url = baseUrl + "/categories/" + id;
const response = await fetch(url);
if (!response.ok) {
return;
}
const category = await response.json();
setTitle(category.name);
}
if (loadingPosts) {
return (
<IonPage>
<IonHeader translucent={true}>
</IonHeader>
<IonContent>
{page === 1 ? <Slider listOfPosts={posts}/> : <div/>}
<Posts
listOfPosts={posts}
totPages={totPages}
handleClickNextPage={handleClickNextPage}
pageNumber={page}
/>
</IonContent>
</IonPage>
);
} else {
return <IonLoading
isOpen={!loadingPosts}
message={ION_LOADING_DIALOG}
duration={ION_LOADING_DURATION}
/>
}
}
are there any settings belonging to the rest api? The call is to a URL with https. When I remove the useefect and only render a static page without content, it works fine.

Answer 1

At the End it was a CORS error on Endpoint. I had to allow cordova://localhost on Endpoint.