The data source helpers used with the IGChartView allow you to specify property paths should you want to use a custom object contained within an array. Below I've pasted code from the implementation file to help you get started. If you have any further questions don't hesitate to ask.

#import "igViewController.h"
#import <IGChart/IGChart.h>

@interface GraphObject : NSObject
   @property (nonatomic,retain) NSString *territory;
   @property (nonatomic, assign) double cost;
@end

@implementation GraphObject
   @synthesize cost, territory;
@end

@interface igViewController ()
{
    IGChartView *_chart;
   NSMutableArray *_data;
   IGCategorySeriesDataSourceHelper *_source;
}

@end

@implementation igViewController

- (void)viewDidLoad
{
   [super viewDidLoad];

   _data = [[NSMutableArray alloc] init];
   [self generateData];

   _source = [[IGCategorySeriesDataSourceHelper alloc] init];
   _source.data = _data;
   _source.valuePath = @"cost";
   _source.labelPath = @"territory";

   _chart = [[IGChartView alloc] initWithFrame:CGRectInset(self.view.frame, 30.0, 30.0)];
   [_chart setAutoresizingMask:UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight];
   _chart.theme = [IGChartGradientThemes IGThemeDark];
   _chart.delegate = self;
   [self.view addSubview:_chart];

   [_chart addSeriesForType:[IGColumnSeries class] usingKey:@"series" withDataSource:_source firstAxisKey:@"xAxis" secondAxisKey:@"yAxis"];
}

- (void)didReceiveMemoryWarning
{
   [super didReceiveMemoryWarning];
}

-(void)generateData
{
   NSArray *territories = [NSArray arrayWithObjects:@"Canada", @"Finland", @"Holland", @"Japan", @"USA", nil];

   for (int i = 0; i < 5; i++)
   {
      GraphObject *graphObject = [[GraphObject alloc] init];
      graphObject.territory = [territories objectAtIndex:i];
      graphObject.cost = arc4random() % 100000;
      [_data addObject:graphObject];
   }
}

- (NSString *)chartView:(IGChartView *)chartView labelForAxis:(IGAxis *)axis withItem:(NSObject *)item
{
   if([axis.key isEqualToString:@"xAxis"])
      //item for this axis is an IGCategoryPoint
      return ((IGCategoryPoint *)item).label;
   else if ([axis.key isEqualToString:@"yAxis"])
   {
      //item for this axis is a NSNumber
      NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
      [formatter setNumberStyle:NSNumberFormatterCurrencyStyle];
      return [formatter stringFromNumber:(NSNumber *)item];
   }

   return nil;

}

@end