uniapp input输入框 在IOS手机无法自动获取焦点

//HTML
<input v-show="flag" class="uni-input" :focus="flag" type="text" v-model="keyword" placeholder="请输入搜索条件"  placeholder-class="placeholder"/>


//JS
data() {
 return {
  flag:false,
  keyword:''
 }
},
async mounted() {
    await this.$nextTick()
    this.flag = true
 },