el: 需要复制的内容dom，应为input
if （/(iPhone|iPad|iPod|iOS)/i.test(navigator.userAgent)) {
const editable = el.contentEditable;
el.contentEditable = true;
el.readOnly = true;
const range = document.createRange();
range.selectNodeContents(el);
const sel = window.getSelection();
sel.removeAllRanges();
sel.addRange(range);
el.setSelectionRange(0, 50); // 这里setSelectionRange第二个参数必须为正数，负数不生效
el.contentEditable = editable;
} else {
const text = document.getElementById(id);
text.focus();
text.setSelectionRange(0, 99999); // 这里setSelectionRange第二个参数必须为正数，负数不生效
}
document.execCommand(‘copy‘);
el.blur();
点击按钮复制，移动端ios兼容
原文：https://www.cnblogs.com/axl-study/p/11577943.html
