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];
 }
}