Iscroll IOS cannot slide

<div id="scroll" class="scroll">
   <div id="modal-body" class="modal-body"></div>
</div>
.scroll {
      position: relative;
      line-height: 1.6;
      height: 5rem;
    }
    .modal-body {
      line-height: 1.6;
      padding: 10px 0;
      font-size: 120%;
      overflow-y: scroll;
      -webkit-overflow-scrolling: touch;
    }
$("-sharprule").on("click", function () {
      $(".modal").show();
      if (!haveScroll) {
        new IScroll("-sharpscroll", {
          mouseWheel: true,
          scrollY: true,
          tap: true
        });
        haveScroll = true;
      }
    });

Android has no problem to slide, but IOS can"t slide. What"s going on? ask for guidance

.
Apr.22,2021

the problem has been solved.
to prevent body from sliding,
adds the following code to Android, while IOS does not add

$(".modal").on("touchmove", function (e) {
   e.preventDefault();
});
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