Just create an interface by following this code.

@interface MREntitiesConverter : NSObject {
NSMutableString* resultString;
}
@property (nonatomic, retain) NSMutableString* resultString;
- (NSString*)convertEntiesInString:(NSString*)s;
@end

@implementation MREntitiesConverter
@synthesize resultString;
- (id)init
{
if([super init]) {
//resultString = [[NSMutableString alloc] init];
}
return self;
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)s [...]

This can be done easily just like when you are working with the standard ViewController.

Here is the sample code…

UIAlertView *alert = [[UIAlertView alloc] init];
[alert setTitle:@"My Title"];
[alert setMessage:@"My message"];
[alert setDelegate:self];
[alert addButtonWithTitle:@"OK"];
[alert addButtonWithTitle:@"Cancel"];
[alert [...]