gistfile1.m

@interface Foo : NSObject
{
    NSData* _data;
}
@end

@implementation Foo

- (void) download
{
    NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://tut.by"]];
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
        _data = data;
    }];
}

@end