You can sort by "PublishDate".
// ascending NO: from the largest to the smallest number
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"PublishDate" ascending:NO];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
NSArray *sortedArray = [arr sortedArrayUsingDescriptors:sortDescriptors];