iOS Symbol(s) not found error

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
#import "Settings.h"



@interface FinalProjectViewController : UIViewController {
	

	UIButton *myButton;
	AVAudioPlayer *audioPlayer;

}

@property (nonatomic, retain) UIButton *myButton;
@property (nonatomic, retain) AVAudioPlayer *audioPlayer;

-(IBAction) playButtonPressed;
-(IBAction) pauseButtonPressed;

-(IBAction) settingsPressed;
@end

#import "FinalProjectViewController.h"

@implementation FinalProjectViewController

@synthesize myButton;
@synthesize audioPlayer;

- (void)viewDidLoad {
    [super viewDidLoad];
	
	NSString *filePath = [[NSBundle mainBundle] pathForResource:@"SecretAgent" ofType:@"mp3"];
	
	NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:filePath];
	
	audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:nil];
	
	[filePath release];
	
	[fileURL release];
	
	[audioPlayer prepareToPlay];
}

-(IBAction) playButtonPressed {
	[audioPlayer play];
	
}
						
-(IBAction) pauseButtonPressed {
	[audioPlayer pause];
							
}
						
						
						
-(IBAction) settingsPressed {
	Settings *myOtherView = [[Settings alloc] init];
	myOtherView.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
	[self presentModalViewController:myOtherView animated:YES];
	[myOtherView release];
}	



- (void)didReceiveMemoryWarning {
	// Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
	
	// Release any cached data, images, etc that aren't in use.
}

- (void)viewDidUnload {
	// Release any retained subviews of the main view.
	// e.g. self.myOutlet = nil;
}


- (void)dealloc {
    [super dealloc];
	[myButton release];
	[audioPlayer release];
}

@end

Undefined symbols:
  "_OBJC_CLASS_$_AVAudioPlayer", referenced from:
      objc-class-ref-to-AVAudioPlayer in FinalProjectViewController.o
ld: symbol(s) not found
collect2: ld returned 1 exit status