小程序版本。ios按home键后，后台还在执行，怎么停止这个
clearCountDown() {
console.log('clearCountDown：==》')
if(_this.countDownFun != null){
clearInterval(_this.countDownFun);
_this.countDownFun = null;
}
},
onUnload() {
_this.clearCountDown();
},
onHide() {
if(_this.no_sumbit){
clearInterval(_this.countDownFun);
_this.countDownFun = null;
// _this.clearCountDown();
console.log('onHide:')
}
console.log('onHide')
},
onShow() {
if(_this.no_sumbit){
_this.DocumentTime();
}
console.log('onShow')
},
