原因：vue3中es6语法，iphone6-iOS12.4不支持

解决方法：babel.config.js改为以下配置

module.exports = {
  presets: [
    '@vue/cli-plugin-babel/preset','@babel/preset-env'
  ],
  plugins: ['@babel/plugin-transform-runtime'],
 
}

package.json改为："browserslist": [
      "> 1%",
        "last 2 versions",
        "not dead",
        "not ie 11",
        "ios >= 9"
  ]