Question

I’m using JSON to parse data into an NSArray ‘courseArray’. I then filter this data using NSPredicate and store it into ‘rows’. The problem is, i dont know how to determine if ‘rows’ is empty or not. For example : If a record exists, rows will contain the appropriate objects, but if the record doesnt exist then the application crashes (also when i use NSLog to see the contents of the array its blank, i believe its supposed to say its nil? if there are no objects). How can i fix this?

if (dict)
{
    courseArray  = [[dict objectForKey:@"lab"] retain];
    NSPredicate* predicate = [NSPredicate predicateWithFormat:@"labNumber== %@",labSelected]; //filter
    rows = [[courseArray filteredArrayUsingPredicate:predicate]retain];
}

[jsonreturn release];

self.formattedTextView.opaque = NO;
self.formattedTextView.backgroundColor = [UIColor clearColor];

NSLog(@"array %@",rows);

 **NSDictionary *currentSelection = [rows objectAtIndex:0];** (app crashes at this line - [NSArray objectAtIndex:]: index 0 beyond bounds for empty array')
 NSString *labNumber = [currentSelection objectForKey:@"labNumber"];

Answer 1

Try if([courseArray count] > 0) also another method that can be of help here is

[courseArray containsObject:(id)]