UITableView Delete When the crash Nsscanner:nil string argument

It's been a day of breaking up today, and it's worth remembering.

-(void) TableView: (UITableView *) TableView Commiteditingstyle: (uitableviewcelleditingstyle) Editingstyle Forrowatindexpath: (Nsindexpath *) Indexpath

{

if (_segment.selectedsegmentindex = = 0) {

[_allarray RemoveObjectAtIndex:indexPath.row];

[TableView Deleterowsatindexpaths:@[indexpath] withrowanimation:uitableviewrowanimationautomatic];

Data source _allarray is retrieved from the background
Is this: in the TableView to delete a row when the crash, what crash information is not, is a sentence, nsscanner:nil string argument, how to find a bug, then a flash, add a sentence

Self.allarray = [Nsmutablearray arraywitharray:[dic objectforkey:@ "data"]]; How to solve the idea of how to think, I defined is a variable array, from the background to obtain data after the assignment to Self.array, how can he become immutable? The bug is solved, but the problem does not understand, later still pay attention to point