Fill up table view with UISearchDisplayController leads to EXC_BAD_ACESS! WHY? - objective-c

Question

I made some test with the UISearchDisplayController and I found some strange behavior I can not explain properly.
Please take a look at the following code:
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return numOfRecords;
}
- (NSArray*) search:(NSString*)query {
// Prepare URL request to download statuses from Twitter
NSString *urlString = [NSString stringWithFormat:#"http://someaddress/search.ac?term=%#", query];
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:urlString]];
// Perform request and get JSON back as a NSData object
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
// Get JSON as a NSString from NSData response
NSString *json_string = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
NSArray *parsedResult = [json_string JSONValue];
return parsedResult;
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *kCellID = #"cellID";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kCellID];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:kCellID] autorelease];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
int i = [indexPath row];
if ( i >= [searchResult count] ) return cell;
NSString *res = [searchResult objectAtIndex:i];
[[cell textLabel] setText:res];
return cell;
}
- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString {
// WEB Request
NSArray *entries = [self search:searchString];
numOfRecords = [entries count];
NSMutableArray *entryTitles = [[NSMutableArray alloc] init];
for (int i=0; i<numOfRecords; i++) {
NSDictionary *entry = [entries objectAtIndex:i];
[entryTitles addObject:[entry objectForKey:#"title"]];
}
searchResult = entryTitles;
return YES;
}
The searchResult variable is a member variable of type NSArray. This code works fine, however if I change the assignment of searchResult to
searchResult = [NSArray arrayWithArray: entryTitles];
The program crashes after typing the second letter in the search field with a EXC_BAD_ACCESS.
Can somebody explain what is the problem that causes this error?

Answer 1

You probably just need to retain it:
searchResult = [[NSArray arrayWithArray: entryTitles] retain];
You need to do this because arrayWithArray just creates an autoreleased object that will be released in the near future. You need to add your retain to take ownership.
Once you've taken ownership, don't forget to release it somewhere.

Answer 2

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString {
// WEB Request
NSArray *entries = [self search:searchString];
[searchResult autorelease];
searchResult = [[entries valueForKeyPath:"#unionOfObjects.title"] retain];
return YES;
}

Answer 3

I ran across the same issue. My problem was that in cellForRowAtIndexPath I was releasing the object in the search results array after loading the string value into the cell for display.
Consequently, when I tried to search for anything it immediately crashed.
Check to make sure you aren't releasing the objects that you are searching against.