Coding IOS, error in code

//
//  ViewController.m
//  CrystalBall
//
//  Created by Owner on 12/25/12.
//  Copyright (c) 2012 com.toptechnow. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController
@synthesize PredictionLabel;

- (void)viewDidLoad

{
[super viewDidLoad];
    self->predictionArray = [ [NSArray alloc] initWithObjects:@"It is certain",@"It is decidedly so" ,@"All signs say YES",
                                @"the stars are not aligned"
                                @"My reply is no",
                                @"It is doubtful",
                                @"Better not tell you now",
                                @"Concentrate and ask again",
                                @"Unable to answer now", nil];
}

- (void)viewDidUnload
{
    [self setPredictionLabel:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    //Return Yes for supported orientations
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

- (IBAction)ButtonPressed:(UIButton *)sender {

self->predictionArray = [self->predictionArray objectAtIndex:3];
}
@end