let timeline = this.timelineRef.nativeElement;
if( ios ) {
let position = UITableViewScrollPosition.UITableViewScrollPositionMiddle;
let animated = false;
let nsIndex = NSIndexPath.indexPathForItemInSection(index, 0);
timeline.ios.scrollToRowAtIndexPathAtScrollPositionAnimated(nsIndex, position, animated);
} else( android ) {
let itemHeight = timeline.android.getChildAt(index).getHeight();
let offset = timeline.android.getHeight() / 2 - itemHeight / 2;
timeline.android.smoothScrollToPositionFromTop(index, offset, 0);
}