More generally, if you previously used http.get(someString), http.post(someString), etc. you instead will need to use http.get(Uri.parse(someString)), http.post(Uri.parse(someString)), and so on. (package:http formerly called Uri.parse internally to convert a String into a Uri for you.)in url case use:
var response = await http.get(Uri.parse(url));
in widgets use:
Text(data[index]['name'].toString())await http.post(
Uri.parse("https://api.instagram.com/oauth/access_token"),
body: {
"client_id": clientID,
"redirect_uri": redirectUri,
"client_secret": appSecret,
"code": authorizationCode,
"grant_type": "authorization_code",
});