add CheckInCounter component to read contract variable checkedInCounter

packages/nextjs/app/page.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import Link from "next/link";
+import CheckedInCounter from "../components/CheckedInCounter";
 import type { NextPage } from "next";
 import { BugAntIcon, MagnifyingGlassIcon } from "@heroicons/react/24/outline";
 
@@ -15,8 +16,7 @@ const Home: NextPage = () => {
           </h1>
           <p className="text-center text-lg">Get started by taking a look at your batch GitHub repository.</p>
           <p className="text-lg flex gap-2 justify-center">
-            <span className="font-bold">Checked in builders count:</span>
-            <span>To Be Implemented</span>
+            <CheckedInCounter />
           </p>
         </div>
 

packages/nextjs/components/CheckedInCounter.tsx

@@ -0,0 +1,34 @@
+import { useEffect, useState } from "react";
+import { useScaffoldReadContract } from "~~/hooks/scaffold-eth";
+
+const CheckInCount = () => {
+  const [feedback, setFeedback] = useState<string>("");
+  const [result, setResult] = useState<string>();
+
+  const {
+    data: checkedIn,
+    isLoading: checkInLoading,
+    error: checkInError,
+  } = useScaffoldReadContract({
+    contractName: "BatchRegistry",
+    functionName: "checkedInCounter",
+  });
+
+  useEffect(() => {
+    if (checkInError) {
+      setFeedback("Something went wrong");
+      console.error(checkInError);
+    } else {
+      setResult(checkInLoading ? "..." : String(Number(checkedIn)));
+    }
+  });
+
+  return (
+    <>
+      <span className="font-bold">Checked in builders count: {result}</span>
+      {feedback && <p>{feedback}</p>}
+    </>
+  );
+};
+
+export default CheckInCount;