Custom displayFormat on ion-datetime

In my app I need to select a week. Since I couldn’t find a week picker I let user pick a date and using MomentJS I create range
getWeekRange(date){
return moment(date).startOf(‘isoWeek’).format(‘DD’) + “-” + moment(date).endOf(‘isoWeek’).format(‘DD MMM YYYY’)
}

I want to display this result (23-29 Jan 2017) instead of displayFormat.

If anybody can help me with this I’d appreciate it.