在使用之前判断过接口要求大于2.0.4

错误信息

wx.createBannerAd is not a function. (In ‘wx.createBannerAd({adUnitId:“adunit-”,style:{left:0,top:e.screenHeight-100-n,width:e.screenWidth,height:70}})’, ‘wx.createBannerAd’ is undefined);at setTimeout callback function