场景由于各种产品需求的变动，我们在项目里一般情况下会用系统的UIAlertController，当然有很多特别的需求，所以我们就定义了一些view来做成美工需求的样式，还有些我们定义了一个AlertController和UIAlertController相似度特别高，那么问题来了，截屏时，有些只能截屏到弹窗，还有只能截屏到弹窗下面的那个控制器的view。想来想去，只能把所有窗口从后往前一直截屏然后叠加，但是用全英文在谷歌没有搜索到适合的东西，好在同事用汉字在百度找到了可用的代码。记录一下。有时候遇到问题，我们可以适当地切换一下谷歌和百度，适当地切换一下中文关键字和英文关键字。

截取当前屏幕内容 将以下代码粘贴复制 直接调用imageWithScreenshot方法

/**
 *  截取当前屏幕
 *
 *  @return NSData *
 */
- (NSData *)dataWithScreenshotInPNGFormat
{
    CGSize imageSize = CGSizeZero;
    UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;
    if (UIInterfaceOrientationIsPortrait(orientation))
        imageSize = [UIScreen mainScreen].bounds.size;
    else
        imageSize = CGSizeMake([UIScreen mainScreen].bounds.size.height, [UIScreen mainScreen].bounds.size.width);
    
    UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
    CGContextRef context = UIGraphicsGetCurrentContext();
    for (UIWindow *window in [[UIApplication sharedApplication] windows])
    {
        CGContextSaveGState(context);
        CGContextTranslateCTM(context, window.center.x, window.center.y);
        CGContextConcatCTM(context, window.transform);
        CGContextTranslateCTM(context, -window.bounds.size.width * window.layer.anchorPoint.x, -window.bounds.size.height * window.layer.anchorPoint.y);
        if (orientation == UIInterfaceOrientationLandscapeLeft)
        {
            CGContextRotateCTM(context, M_PI_2);
            CGContextTranslateCTM(context, 0, -imageSize.width);
        }
        else if (orientation == UIInterfaceOrientationLandscapeRight)
        {
            CGContextRotateCTM(context, -M_PI_2);
            CGContextTranslateCTM(context, -imageSize.height, 0);
        } else if (orientation == UIInterfaceOrientationPortraitUpsideDown) {
            CGContextRotateCTM(context, M_PI);
            CGContextTranslateCTM(context, -imageSize.width, -imageSize.height);
        }
        if ([window respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)])
        {
            [window drawViewHierarchyInRect:window.bounds afterScreenUpdates:YES];
        }
        else
        {
            [window.layer renderInContext:context];
        }
        CGContextRestoreGState(context);
    }
    
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return UIImagePNGRepresentation(image);
}

/**
 *  返回截取到的图片
 *
 *  @return UIImage *
 */
- (UIImage *)imageWithScreenshot
{
    NSData *imageData = [self dataWithScreenshotInPNGFormat];
    return [UIImage imageWithData:imageData];
}