vue根据值给予不同class的实例

<div class="chatBox-kuang" :class="addclass(skin)">
</div>
 
data(){
 return{
  skin:''
 }
}
onchooseSkin(attr){
 this.skin=attr
}, 

addclass(i){
 switch (i) {
  case 0:
   return 'skinA';
  case 1:
   return 'skinB';
  case 2:
   return 'skinC';
 }
}

addclass(i){
 var arr = ['skinA','skinB','skinC'];
 if(i==-1){
  return 'skinA'
 }else{
  return arr[i];
 }
}