OC 获取启动页

有的时候我们需要在启动页上做动画，首先我们放一个启动页的背景图，然后再写一个View做动画。看起来就像启动页动画一样。因为启动页有很多的尺寸，不能在View上直接放一个背景图，会有偏差。
说一下如何获取启动页

- (UIImageView *)imageView
{
    if (!_imageView) {
        NSString *viewOrientation = @"Portrait";//竖屏
        if (UIInterfaceOrientationIsLandscape([[UIApplication sharedApplication] statusBarOrientation])) {
            viewOrientation = @"Landscape";//横屏
        }
        NSString *launchImageName = nil;
        NSArray* imagesDict = [[[NSBundle mainBundle] infoDictionary] valueForKey:@"UILaunchImages"];
        
        UIWindow *currentWindow = [[UIApplication sharedApplication].windows firstObject];
        CGSize viewSize = currentWindow.bounds.size;
        for (NSDictionary* dict in imagesDict)
        {
            CGSize imageSize = CGSizeFromString(dict[@"UILaunchImageSize"]);
            if (CGSizeEqualToSize(imageSize, viewSize) && [viewOrientation isEqualToString:dict[@"UILaunchImageOrientation"]])
            {
                launchImageName = dict[@"UILaunchImageName"];
            }
        }
        UIImage *image = [UIImage imageNamed:launchImageName] ?: OAXUIImage(@"启动页");
        _imageView = [[UIImageView alloc] initWithImage:image];
    }
    return _imageView;
}