NSSortDescriptor 排序

for (int index = 0; index < [_accountGroup count]; index++) {
        NSMutableArray *accountArrayForSection = [theAccountSection objectAtIndex:index];
        NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES];
        NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:&sortDescriptor count:1];
        [accountArrayForSection sortUsingDescriptors:sortDescriptors]; or NSArray * theSortedArray = [accountArrayForSection sortedArrayUsingDescriptors:sortDescriptors]
        [sortDescriptor release];
        [sortDescriptors release];
    }