objectAtIndex:indexPath.row method always causes exception in IOS - ios

Question

Hi I always seem to get exception when I use objectAtInded method to retrieve NSString from an array. I am reading data from a dictionary which is in the "PropertyList.plist" file.My code is
- (void)viewDidLoad
{
[super viewDidLoad];
NSString *path = [[NSBundle mainBundle] pathForResource:#"PropertyList"
ofType:#"plist"];
names = [[NSDictionary alloc]
initWithContentsOfFile:path];
keys = [[[names allKeys] sortedArrayUsingSelector:
#selector(compare:)] retain];
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSUInteger section = [indexPath section];
NSUInteger row = [indexPath row];
NSString *key = [keys objectAtIndex:section];
NSArray *nameSection = [names objectForKey:key];
static NSString *SectionsTableIdentifier = #"SectionsTableIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:SectionsTableIdentifier];
if(cell == nil)
{
cell = [[[UITableViewCell alloc]
initWithStyle:UITableViewCellStyleDefault reuseIdentifier:SectionsTableIdentifier] autorelease];
}
cell.textLabel.text = [nameSection objectAtIndex:row];
return cell;
}
The exception happens on the method "cellForRowAtIndexPath" in the line
cell.textLabel.text = [nameSection objectAtIndex:row];
The error message is
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFDictionary objectAtIndex:]: unrecognized selector sent to instance 0x6832440
The plist file is
Where ever I use "[nameSection objectAtIndex:row];" type of statement it always get exception.

Answer 1

The reason for this can be following
[names objectForKey:key];. This statement could give output a NSMutableDictionary type and you are taking a NSArray from that. OR
If it is an array then use the below code for getting the nameSection
NSMutableArray *nameSection = (NSMutableArray*)[names objectForKey:key];
// using (NSMutableArray*) before the code is for external typecasting to tell the compiler that the output is of NSMutableArray type.
Hope this helps.
EDIT:-
use the method below to get your dictionary from the plist file
-(NSMutableDictionary *) GetDictDataFromPlistFile:(NSString *) fileName
{
NSError *error;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); //1
NSString *documentsDirectory = [paths objectAtIndex:0]; //2
NSString *path = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.plist",fileName]]; //3
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath: path]) //4
{
NSString *bundle = [[NSBundle mainBundle] pathForResource:fileName ofType:#"plist"]; //5
[fileManager copyItemAtPath:bundle toPath: path error:&error]; //6
}
NSMutableDictionary *dictData = [[NSMutableDictionary alloc] initWithContentsOfFile:path];
return dictData;
}

Answer 2

Here, name contains only one key of root.
What you need for name is the value of key Root.
Please retry!

Answer 3

Like #scorpiozj said 'names' contains only key of 'Root'. So what I did I know is not a very good way to do it. I am sure there is some other way. I changed the 'viewDidLoad' method to this,
- (void)viewDidLoad
{
[super viewDidLoad];
NSString *path = [[NSBundle mainBundle] pathForResource:#"PropertyList"
ofType:#"plist"];
names = [[NSDictionary alloc]
initWithContentsOfFile:path];
keys = [names allKeys];
NSString *key = [keys objectAtIndex:0];
names = [names objectForKey:key];
keys = [[[names allKeys] sortedArrayUsingSelector:#selector(compare:)] retain];
NSLog(#"keys = %# names = %#",keys,names);
}
It works! Any idea how to do it better will be appreciated though.