Check key exists in NSDictionary

I presume that [dataArray objectAtIndex:indexPathSet.row] is returning an NSDictionary, in which case you can simply check the result of valueForKey against nil.

For example:

if ([[dataArray objectAtIndex:indexPathSet.row] valueForKey:@"SetEntries"] != nil) {
    // The key existed...

}
else {
    // No joy...

}