Strange data-binding issue in iOS

Hi, I am using ionic in a application where I have a page which bind some values from controller.

IN the first image the binding works fine which is the behaviour in android, but in ios some other data is appended within the binding, when I console the value it doesn’t show any value. But the view have this problem of appending some random data.
Controller code:
ref.year =;
ref.prevYear = function() {
ref.year = ref.year-1;
ref.nextYear = function() {
ref.year = ref.year+1;
View template

              <a ng-click="vm.prevYear();" class="align_left"><i class="icon"><img src="image/arrow-left.png" /></i><span>{{vm.year-1}}</span></a>
              <h2 class="title">{{vm.year}}</h2>
              <a ng-click="vm.nextYear();" class="align_right"><span>{{vm.year+1}}</span><i class="icon"><img src="image/arrow-right.png" /></i></a>

Please help me on this issue, this is mission critical for me. I can’t find any solutions online and I can’t even figure how to search for an issue like this.