Ios 从CVImageBufferRef创建CIImage

我正在尝试从

CVPixelBuffer

创建一个

CIImage

对象，直到第3步，一切都进行得很顺利

但在步骤4：

[[CIImage alloc] initWithCVPixelBuffer:imageBuffer options:(__bridge_transfer NSDictionary *)attachments] 

返回零。
所以，请为我的问题提供解决方案……提前谢谢

CMSampleBufferRef sampleBufferRef = [readerVideoTrackOutput copyNextSampleBuffer];

CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

CFDictionaryRef attachments = CMCopyDictionaryOfAttachments(kCFAllocatorDefault,        
                            sampleBuffer, kCMAttachmentMode_ShouldPropagate);
CIImage *image = [[CIImage alloc] initWithCVPixelBuffer:imageBuffer options:(__bridge_transfer NSDictionary *)attachments];

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你在模拟器上运行这个吗？