iPhone:获取相机预览

Question

我想在用户使用相机时获取UIImagePickerController上显示的图像.当我得到我想要处理图像和显示而不是常规的相机视图.

但问题是当我想要获取相机视图时,图像只是一个黑色矩形.

这是我的代码:

UIView *cameraView = [[[[[[imagePicker.view subviews] objectAtIndex:0]
                         subviews] objectAtIndex: 0]
                       subviews] objectAtIndex: 0];

UIGraphicsBeginImageContext( CGSizeMake(320, 427) );
[cameraView.layer renderInContext: UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

imageToDisplay.image = [PixelProcessing processImage: viewImage];   //In this case the image is black
//imageToDisplay.image = viewImage; //In this case the image is black too
//imageToDisplay.image = [UIImage imageNamed: @"icon.png"];     //In this case image is being displayed properly

我究竟做错了什么？

谢谢.

Answer 1

这个也很好用.打开相机预览时使用它:

UIImage *viewImage = [[(id)objc_getClass("PLCameraController") 
                      performSelector:@selector(sharedInstance)] 
                      performSelector:@selector(_createPreviewImage)];

但据我所知,它带来的结果与以下采用当前屏幕截图的解决方案相同:

extern CGImageRef UIGetScreenImage();

CGImageRef cgoriginal = UIGetScreenImage();
CGImageRef cgimg = CGImageCreateWithImageInRect(cgoriginal, rect);            
UIImage *viewImage = [UIImage imageWithCGImage:cgimg];    
CGImageRelease(cgoriginal);                
CGImageRelease(cgimg);  

我还没有找到修复的问题是,如何在没有任何叠加的情况下快速获得相机图像？