baseAddress是不安全的可变指针，或更确切地说是UnsafeMutablePointer<Void>。将指针转换Void为更特定的类型后，即可轻松访问内存：
// Convert the base address to a safe pointer of the appropriate type
let byteBuffer = UnsafeMutablePointer<UInt8>(baseAddress)
// read the data (returns value of type UInt8)
let firstByte = byteBuffer[0]
// write data
byteBuffer[3] = 90
确保使用正确的类型（8、16或32位unsigned int）。这取决于视频格式。最有可能是8位。
您可以在初始化AVCaptureVideoDataOutput实例时指定格式。您基本上可以选择：
如果您对颜色值和速度（或更确切地说，最大帧速率）不感兴趣，那么请选择更简单的BGRA格式。否则，请选择一种更有效的本机视频格式。
如果有两个平面，则必须获取所需平面的基址（请参见视频格式示例）：
let pixelBuffer: CVPixelBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer)!
CVPixelBufferLockBaseAddress(pixelBuffer, 0)
let baseAddress = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0)
let bytesPerRow = CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 0)
let byteBuffer = UnsafeMutablePointer<UInt8>(baseAddress)
// Get luma value for pixel (43, 17)
let luma = byteBuffer[17 * bytesPerRow + 43]
CVPixelBufferUnlockBaseAddress(pixelBuffer, 0)
let pixelBuffer: CVPixelBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer)!
CVPixelBufferLockBaseAddress(pixelBuffer, 0)
let baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer)
let int32PerRow = CVPixelBufferGetBytesPerRow(pixelBuffer)
let int32Buffer = UnsafeMutablePointer<UInt32>(baseAddress)
// Get BGRA value for pixel (43, 17)
let luma = int32Buffer[17 * int32PerRow + 43]
CVPixelBufferUnlockBaseAddress(pixelBuffer, 0)
602392714
清零编程群