那是因为你的前置摄像头捕捉到了翻转的图像，就像镜子一样。你需要做的是在捕捉图像后固定图像方向。

雨燕3

extension UIImage {

func fixOrientation() -> UIImage {

    // No-op if the orientation is already correct
    if ( self.imageOrientation == UIImageOrientation.up ) {
        return self;
    }

    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    var transform: CGAffineTransform = CGAffineTransform.identity

    if ( self.imageOrientation == UIImageOrientation.down || self.imageOrientation == UIImageOrientation.downMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: self.size.height)
        transform = transform.rotated(by: CGFloat(Double.pi))
    }

    if ( self.imageOrientation == UIImageOrientation.left || self.imageOrientation == UIImageOrientation.leftMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: 0)
        transform = transform.rotated(by: CGFloat(Double.pi / 2.0))
    }

    if ( self.imageOrientation == UIImageOrientation.right || self.imageOrientation == UIImageOrientation.rightMirrored ) {
        transform = transform.translatedBy(x: 0, y: self.size.height);
        transform = transform.rotated(by: CGFloat(-Double.pi / 2.0));
    }

    if ( self.imageOrientation == UIImageOrientation.upMirrored || self.imageOrientation == UIImageOrientation.downMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)
    }

    if ( self.imageOrientation == UIImageOrientation.leftMirrored || self.imageOrientation == UIImageOrientation.rightMirrored ) {
        transform = transform.translatedBy(x: self.size.height, y: 0);
        transform = transform.scaledBy(x: -1, y: 1);
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    let ctx: CGContext = CGContext(data: nil, width: Int(self.size.width), height: Int(self.size.height),
                                   bitsPerComponent: self.cgImage!.bitsPerComponent, bytesPerRow: 0,
                                   space: self.cgImage!.colorSpace!,
                                   bitmapInfo: self.cgImage!.bitmapInfo.rawValue)!;

    ctx.concatenate(transform)

    if ( self.imageOrientation == UIImageOrientation.left ||
        self.imageOrientation == UIImageOrientation.leftMirrored ||
        self.imageOrientation == UIImageOrientation.right ||
        self.imageOrientation == UIImageOrientation.rightMirrored ) {
        ctx.draw(self.cgImage!, in: CGRect(x: 0,y: 0,width: self.size.height,height: self.size.width))
    } else {
        ctx.draw(self.cgImage!, in: CGRect(x: 0,y: 0,width: self.size.width,height: self.size.height))
    }

    // And now we just create a new UIImage from the drawing context and return it
    return UIImage(cgImage: ctx.makeImage()!)
}

}
用作

let myImage = picCaptured.fixOrientation()

然后对该图像应用CIFilter

在应用滤镜之前，请确保图像大小意味着宽度应小于高度，因为从前置摄像头拍摄的图像/照片的宽度大于长度，这可能会在应用滤镜后导致问题。https://developer.apple.com/library/content/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Cameras/Cameras.html

Abdul Waheed针对Swift 5.5的解决方案：

func fixOrientation() -> UIImage {
// No-op if the orientation is already correct
if ( self.imageOrientation == UIImage.Orientation.up ) {
  return self;
}

// We need to calculate the proper transformation to make the image upright.
// We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
var transform: CGAffineTransform = CGAffineTransform.identity

if ( self.imageOrientation == UIImage.Orientation.down || self.imageOrientation == UIImage.Orientation.downMirrored ) {
  transform = transform.translatedBy(x: self.size.width, y: self.size.height)
  transform = transform.rotated(by: CGFloat(Double.pi))
}

if ( self.imageOrientation == UIImage.Orientation.left || self.imageOrientation == UIImage.Orientation.leftMirrored ) {
  transform = transform.translatedBy(x: self.size.width, y: 0)
  transform = transform.rotated(by: CGFloat(Double.pi / 2.0))
}

if ( self.imageOrientation == UIImage.Orientation.right || self.imageOrientation == UIImage.Orientation.rightMirrored ) {
  transform = transform.translatedBy(x: 0, y: self.size.height);
  transform = transform.rotated(by: CGFloat(-Double.pi / 2.0));
}

if ( self.imageOrientation == UIImage.Orientation.upMirrored || self.imageOrientation == UIImage.Orientation.downMirrored ) {
  transform = transform.translatedBy(x: self.size.width, y: 0)
  transform = transform.scaledBy(x: -1, y: 1)
}

if ( self.imageOrientation == UIImage.Orientation.leftMirrored || self.imageOrientation == UIImage.Orientation.rightMirrored ) {
  transform = transform.translatedBy(x: self.size.height, y: 0);
  transform = transform.scaledBy(x: -1, y: 1);
}

// Now we draw the underlying CGImage into a new context, applying the transform
// calculated above.
let ctx: CGContext = CGContext(data: nil, width: Int(self.size.width), height: Int(self.size.height),
                               bitsPerComponent: self.cgImage!.bitsPerComponent, bytesPerRow: 0,
                               space: self.cgImage!.colorSpace!,
                               bitmapInfo: self.cgImage!.bitmapInfo.rawValue)!;

ctx.concatenate(transform)

if ( self.imageOrientation == UIImage.Orientation.left ||
     self.imageOrientation == UIImage.Orientation.leftMirrored ||
     self.imageOrientation == UIImage.Orientation.right ||
     self.imageOrientation == UIImage.Orientation.rightMirrored ) {
  ctx.draw(self.cgImage!, in: CGRect(x: 0,y: 0,width: self.size.height,height: self.size.width))
} else {
  ctx.draw(self.cgImage!, in: CGRect(x: 0,y: 0,width: self.size.width,height: self.size.height))
}

// And now we just create a new UIImage from the drawing context and return it
return UIImage(cgImage: ctx.makeImage()!)}