HTML label 命令在 iPhone 浏览器中不起作用

html
<!DOCTYPE html>
<html>
<head>
  <title>iphone 浏览器中的 <label> 命令问题</title>
  <script>
    function associateLabel() {
      var label = document.getElementById("myLabel");
      var input = document.getElementById("myInput");
      label.addEventListener("click", function() {
        input.focus();
      });
    }
  </script>
</head>
<body onload="associateLabel()">
  <label for="myInput" id="myLabel"><strong>点击我来操作输入框</strong></label>
  <input type="text" id="myInput">
</body>
</html>