[iOS]ディスプレイと画像の比率を求める

- (float)getScale :(CGSize)displaySize :(CGSize)imageSize {
    float scale = 0.0;
    
    if (imageSize.height > displaySize.height) {
        scale = displaySize.height / imageSize.height;
    } else {
        scale = imageSize.height / displaySize.height;
    }
    
    return scale;
}