iOS 5の顔検出機能とカメラを使ったiPhoneアプリを作る

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    // 撮影画像を取得
    UIImage *originalImage = (UIImage *) [info objectForKey:UIImagePickerControllerOriginalImage];
    // 撮影した写真をUIImageViewへ設定
    picture.image = originalImage;
    
    // 検出器生成
    NSDictionary *options = [NSDictionary dictionaryWithObject:CIDetectorAccuracyLow forKey:CIDetectorAccuracy];
    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:options];
    
    // 検出
    CIImage *ciImage = [[CIImage alloc] initWithCGImage:originalImage.CGImage];
    NSDictionary *imageOptions = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:6] forKey:CIDetectorImageOrientation];
    NSArray *array = [detector featuresInImage:ciImage options:imageOptions];
    
    // 検出されたデータを取得
    for (CIFaceFeature *faceFeature in array) {
        // 眼鏡画像追加処理へ
        [self drawMeganeImage:faceFeature];
    }
    
    // カメラUIを閉じる
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (void)drawMeganeImage:(CIFaceFeature *)faceFeature
{
    if (faceFeature.hasLeftEyePosition && faceFeature.hasRightEyePosition && faceFeature.hasMouthPosition) {
    
        // 顔のサイズ情報を取得
        CGRect faceRect = [faceFeature bounds];
        // 写真の向きで検出されたXとYを逆さにセットする
        float temp = faceRect.size.width;
        faceRect.size.width = faceRect.size.height;
        faceRect.size.height = temp;
        temp = faceRect.origin.x;
        faceRect.origin.x = faceRect.origin.y;
        faceRect.origin.y = temp;
    
        // 比率計算
        float widthScale = picture.frame.size.width / picture.image.size.width;
        float heightScale = picture.frame.size.height / picture.image.size.height;
        // 眼鏡画像のxとy、widthとheightのサイズを比率似合わせて変更
        faceRect.origin.x *= widthScale;
        faceRect.origin.y *= heightScale;
        faceRect.size.width *= widthScale;
        faceRect.size.height *= heightScale;
    
        // 眼鏡のUIImageViewを作成
        UIImage *glassesImage = [UIImage imageNamed:@"megane.png"];
        UIImageView *glassesImageView = [[UIImageView alloc]initWithImage:glassesImage];
        glassesImageView.contentMode = UIViewContentModeScaleAspectFit;
 
        // 眼鏡画像のリサイズ
        glassesImageView.frame = faceRect;
    
        // 眼鏡レイヤを撮影した写真に重ねる
        [picture addSubview:glassesImageView];
    }
}