automatic ref counting - NSOutlineView:child:ofItem throws EXC_BAD_ACCESS / loss of object "Item" -

my outlineview crashes exc_bad_access when expand column width - or scroll up/down.

outlineview has controller 4 basic methods:

- (nsinteger)outlineview:(nsoutlineview *)outlineview numberofchildrenofitem:(id)item - (bool)outlineview:(nsoutlineview *)outlineview isitemexpandable:(id)item  - (id)outlineview:(nsoutlineview *)outlineview child:(nsinteger)index ofitem:(id)item - (id)outlineview:(nsoutlineview *)outlineview objectvaluefortablecolumn:(nstablecolumn *)tablecolumn byitem:(id)item  

my app starts displaying contents without problem ,but @ point resizing columns or scrolling, crashes @ :

- (id)outlineview:(nsoutlineview *)outlineview objectvaluefortablecolumn:(nstablecolumn *)tablecolumn byitem:(id)item 

then, item nil. problem. looks arc issue, in controller, own object returned outlineview, either using method

myobject=[nodeobject new]; 

or

myobject =[node copy];    // node != nil checked before 

what's important too: return item directly object. assure outlineview gets non nil objects outlineview:child:ofitem :

- (id)outlineview:(nsoutlineview *)outlineview objectvaluefortablecolumn:(nstablecolumn *)tablecolumn byitem:(id)item { return item; } 

any suggestions @ solve issue welcome !

full samplecode here:

#import "outlinecontroller.h"  @implementation outlinecontroller {  }   // //  items of type hierarchy ! //  - (nsinteger)outlineview:(nsoutlineview *)outlineview numberofchildrenofitem:(id)item {     nsinteger  result=0;     id kvalue=[item anobject];      if (!item) {         result = [[delegate dictdatasource] count];     }     else {         if ( [kvalue iskindofclass:[nsdictionary class]] ||              [kvalue iskindofclass:[nsarray class]]) result=[kvalue count];     }      nslog(@"nbr of childs %ld",(long)result);     return result; }    - (bool)outlineview:(nsoutlineview *)outlineview isitemexpandable:(id)item {     bool  result=no;     id kvalue=[item anobject];      if (!item) {         result = [[delegate dictdatasource] count] > 0 ? yes:no;     }     else {         if ( [kvalue iskindofclass:[nsdictionary class]] ||             [kvalue iskindofclass:[nsarray class]]) result=yes;     }     nslog(@"expandable %d",result);     return result; }   // //  place items created here ! // - (id)outlineview:(nsoutlineview *)outlineview child:(nsinteger)index ofitem:(id)item {     id oneobject;     hierarchy *hchy;      //     // root of type dictionary, , take keys "index"     if ( !item ) {         hchy = [hierarchy new];         [hchy setcomesfromdict:[delegate dictdatasource]];         [hchy setkey:[[[hchy comesfromdict] allkeys ] objectatindex:index] ];         oneobject =[[hchy comesfromdict] valueforkey:[hchy key]];         [hchy setanobject:oneobject];     }     else {         hchy   = [item copy] ;          if ([[hchy anobject] iskindofclass:[nsdictionary class] ]) {             // case: item comes dictionary.             // ( if item expandable, outlineview ask item of index here.             //   dictionary or arrays expandable )              [hchy setkey:[[[hchy anobject] allkeys] objectatindex:index]];             oneobject =[[hchy anobject] valueforkey:[hchy key]];             [hchy setanobject:oneobject];         } else         {             if  ([[hchy anobject] iskindofclass:[nsarray class] ]) {                 // case: item comes anarray                 // fetching array element                 [hchy setcomesfromdict:nil];                 oneobject =[[hchy anobject] objectatindex:index];                 [hchy setanobject:oneobject];                  [hchy setkey:[nsstring stringwithformat:@"%ld",(long)index]];             }else             {   // case: item value                 //                 nslog(@"single kv pair : %@",[hchy key]);                 ;             }         }     }      if ( [[hchy anobject] iskindofclass:[nsarray class] ] ||         [[hchy anobject] iskindofclass:[nsdictionary class] ] ) {         [hchy setvaluetext:@""];         [hchy setisheader:yes];     } else     {        [hchy setvaluetext:[hchy anobject]];     }     return hchy; }  - (id)outlineview:(nsoutlineview *)outlineview objectvaluefortablecolumn:(nstablecolumn *)tablecolumn byitem:(id)item {      return item; }