ios - Maintaining scroll position after reload in tableView -

i've got tableview. when user taps 1 of records, check it's property , basing on i'm filtering results , showing similar results - need refresh tableview.

the problem user can scroll up/down tableview. need scroll tableview cell @ same uitableviewscrollposition before refresh.

obviously, i'm saving last tapped item

- (void)tableview:(uitableview *)tableview didselectrowatindexpath:(nsindexpath *)indexpath {     _lastselecteditem = [self itemforindexpath:indexpath]; }  

then after reloading tableview:

nsindexpath *indexpath = [self indexpathforitem:_lastselecteditem]; if (_tableview.numberofsections > indexpath.section && [_tableview numberofrowsinsection:indexpath.section] > indexpath.row) {     [_tableview scrolltorowatindexpath:indexpath atscrollposition:uitableviewscrollpositionmiddle animated:no];     _lastselecteditem = nil; } 

it but... user not finish @ uitableviewscrollpositionmiddle. have finish scrolling @ uitableviewscrollpositiontop or uitableviewscrollpositionbottom or somewhere between.

-- edit --

calculating via offset problematic, offset difference between start of view , top table scroll position.. while i'm not interested in value :/.

because structure quite complicated finished way (eg. expandable sections etc). please mind, i'm saving _lastselecteditem, object @ datasource, indexpath change after refresh.

- (void)refresh {     [self savelastscrollposition];     [self reloaddata]; // inside reload data + reload tableview     [self scrolltolastscrollposition]; }  - (nsinteger)heighttominyofcellatindexpath:(nsindexpath *)indexpath {     nsinteger sections = indexpath.section;     nsinteger totalrows = 0;     (nsinteger section = 0; section < indexpath.section; section++) {         totalrows += [self.tableview numberofrowsinsection:section];     }     totalrows += indexpath.row;      return ((sections + 1) * kheaderheight + totalrows * krowheight); }  - (void)savelastscrollposition {     if (_lastselecteditem) { // make sure have item selected         nsindexpath *indexpath = [self itemforitem:_lastselecteditem];         nsinteger aboveitemheight = [self heighttominyofcellatindexpath:indexpath];         cgfloat contentoffsety = self.tableview.contentoffset.y;         _previousoffset = aboveitemheight - contentoffsety;     } }  - (void)scrolltolastscrollpostion {     if (_lastselecteditem) { // make sure have item selected         nsindexpath *indexpath = [self itemforitem:_lastselecteditem];         if (self.tableview.numberofsections > indexpath.section && [self.tableview numberofrowsinsection:indexpath.section] > indexpath.row) { // make sure indexpath still exist after reload             nsinteger aboveitemheight = [self heighttominyofcellatindexpath:indexpath]; // height of items above selected index             cgpoint offset = cgpointmake(0.f, aboveitemheight - _previousoffset);             // in case index should higher: eg earlier item @ index (4,8) @ (0,0)             if (offset.y < 0) {                 offset.y = 0;             }             [self.tableview setcontentoffset:offset animated:no]; // jump, user shouldn't see             _previousoffset = 0; // forget calculated values             _lastselecteditem = nil;         }     } }