how to draw line in iphone sdk

////////////////    in .h file   ///////////

CGPoint lastPoint;
    IBOutlet UIImageView *drawImage;
    BOOL mouseSwiped;   
    int mouseMoved;
    UIImageView *currentImage;

}


-(IBAction)eraseButton:(id)sender;
-(IBAction)saveButton:(id)sender;



//////////////    in .m fiel    ///////////


- (void)viewDidLoad
{
    [super viewDidLoad];
    drawImage = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 350)];
    drawImage.image = [UIImage imageNamed:@"splash.png"];
    [self.view addSubview:drawImage];
    //[drawImage addSubview:frontImage];
    self.view.backgroundColor = [UIColor lightGrayColor];
    mouseMoved = 0;
    mouseSwiped = YES;

   
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
   
    mouseSwiped = NO;
    UITouch *touch = [touches anyObject];
   
//    if ([touch tapCount] == 2) {
//        drawImage.image = [UIImage imageNamed:@"splash.png"];
//        return;
//    }
   
    lastPoint = [touch locationInView:self.view];
    lastPoint.y -= 20;
   
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    mouseSwiped = YES;
   
    UITouch *touch = [touches anyObject];
    CGPoint currentPoint = [touch locationInView:self.view];
    currentPoint.y -= 20;
   
   
    UIGraphicsBeginImageContext(self.view.frame.size);
    [drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
    CGContextBeginPath(UIGraphicsGetCurrentContext());
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    [drawImage addSubview:currentImage];
   
    lastPoint = currentPoint;
   
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
   
//    UITouch *touch = [touches anyObject];
//   
//    if ([touch tapCount] == 2) {
//        drawImage.image = [UIImage imageNamed:@"splash.png"];
//        return;
//    }
   
   
    if(!mouseSwiped) {
        UIGraphicsBeginImageContext(self.view.frame.size);
        [drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
        CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
        CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextStrokePath(UIGraphicsGetCurrentContext());
        CGContextFlush(UIGraphicsGetCurrentContext());
        drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
}

-(IBAction)eraseButton:(id)sender{
    drawImage.image = [UIImage imageNamed:@"splash.png"];
}
-(IBAction)saveButton:(id)sender{
    UIImage *image = drawImage.image;
    NSData *imageData = UIImagePNGRepresentation(image); 
    NSFileManager *fileManager = [NSFileManager defaultManager]; 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *fullPath = [documentsDirectory stringByAppendingPathComponent: 
                          [NSString stringWithFormat:@"%@.png", drawImage.image]]; 
   
    [fileManager createFileAtPath:fullPath contents:imageData attributes:nil]; 
    NSLog(@"image saved"); 
   

}