仿ios按钮切换

<div>
    <label><input class="btn-switch" type="checkbox"> 默认未选中</label>
    <label><input class="btn-switch" type="checkbox" checked> 默认选中</label>
    <label><input class="btn-switch btn-switch-animbg" type="checkbox"> 默认未选中,简单的背景过渡效果,加btn-switch-animbg类即可</label>
    <label><input class="btn-switch btn-switch-animbg" type="checkbox" checked> 默认选中</label>
    <label><input class="btn-switch btn-switch-anim" type="checkbox"> 默认未选中，过渡效果，加 btn-switch-anim
        类即可</label>
    <label><input class="btn-switch btn-switch-anim" type="checkbox" checked> 默认选中</label>
</div> 

css:

.btn-switch {
   52px;
  height: 31px;
  position: relative;
  border: 1px solid #dfdfdf;
  background-color: #fdfdfd;
  box-shadow: #dfdfdf 0 0 0 0 inset;
  border-radius: 20px;
  border-top-left-radius: 20px;
  border-top-right-radius: 20px;
  border-bottom-left-radius: 20px;
  border-bottom-right-radius: 20px;
  background-clip: content-box;
  display: inline-block;
  -webkit-appearance: none;
  user-select: none;
  outline: none; }
.btn-switch:before {
  content: '';
   29px;
  height: 29px;
  position: absolute;
  top: 0px;
  left: 0;
  border-radius: 20px;
  border-top-left-radius: 20px;
  border-top-right-radius: 20px;
  border-bottom-left-radius: 20px;
  border-bottom-right-radius: 20px;
  background-color: #fff;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.4); }
.btn-switch:checked {
  border-color: #64bd63;
  box-shadow: #64bd63 0 0 0 16px inset;
  background-color: #64bd63; }
.btn-switch:checked:before {
  left: 21px; }
.btn-switch.btn-switch-animbg {
  transition: background-color ease 0.4s; }
.btn-switch.btn-switch-animbg:before {
  transition: left 0.3s; }
.btn-switch.btn-switch-animbg:checked {
  box-shadow: #dfdfdf 0 0 0 0 inset;
  background-color: #64bd63;
  transition: border-color 0.4s, background-color ease 0.4s; }
.btn-switch.btn-switch-animbg:checked:before {
  transition: left 0.3s; }
.btn-switch.btn-switch-anim {
  transition: border cubic-bezier(0, 0, 0, 1) 0.4s, box-shadow cubic-bezier(0, 0, 0, 1) 0.4s; }
.btn-switch.btn-switch-anim:before {
  transition: left 0.3s; }
.btn-switch.btn-switch-anim:checked {
  box-shadow: #64bd63 0 0 0 16px inset;
  background-color: #64bd63;
  transition: border ease 0.4s, box-shadow ease 0.4s, background-color ease 1.2s; }
.btn-switch.btn-switch-anim:checked:before {
  transition: left 0.3s; }