UITableView and SearchBar problem - cocoa-touch

Question

I'm trying to add a Search bar to my UITableView. I followed this tutorial: http://clingingtoideas.blogspot.com/2010/02/uitableview-how-to-part-2-search.html.
I'm getting this error if I type a letter in the search box: Rooster(10787,0xa05ed4e0) malloc: *** error for object 0x3b5f160: double free
*** set a breakpoint in malloc_error_break to debug.
This error occurs here:
- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString {
[self handleSearchForTerm:searchString];
return YES;
}
(on the second line)
- (void)handleSearchForTerm:(NSString *)searchTerm {
[self setSavedSearchTerm:searchTerm];
if ([self searchResults] == nil) {
NSMutableArray *array = [[NSMutableArray alloc] init];
[self setSearchResults:array];
[array release];
}
//Empty the searchResults array
[[self searchResults] removeAllObjects];
//Check if the searchTerm doesn't equal zero...
if ([[self savedSearchTerm] length] != 0) {
//Search the whole tableList (datasource)
for (NSString *currentString in tableList) {
NSString *klasString = [[NSString alloc] init];
NSInteger i = [[leerlingNaarKlasList objectAtIndex:[tableList indexOfObject:currentString]] integerValue];
if(i != -1) {
klasString = [klassenList objectAtIndex:(i - 1)];
}
//Check if the string matched or the klas (group of school)
if ([currentString rangeOfString:searchTerm options:NSCaseInsensitiveSearch].location != NSNotFound ||
[klasString rangeOfString:searchTerm options:NSCaseInsensitiveSearch].location != NSNotFound) {
//Add to results
[[self searchResults] addObject:currentString];
//Save the klas (group of school). It has the same index as the result (lastname)
NSString *strI = [[NSString alloc] initWithFormat:#"%i", i];
[[self searchResultsLeerlingNaarKlas] addObject:strI];
[strI release];
}
[klasString release];
}
}
}
Can someone help me out?
Regards,
Dodo

Answer 1

The double free error means you have released an object more than needed. Here the suspicious object is klasString.
From your code:
NSString *klasString = [[NSString alloc] init];
...
if(i != -1) {
klasString = [klassenList objectAtIndex:(i - 1)];
}
...
[klasString release];
The assignment inside the if statement
loses reference to the newly allocated NSString, introducing a memory leak
makes the later release apply to the object from klassenList. When klassenList releases its elements, a double free error will occur.