图片采集的方向问题: https://juejin.im/post/5cbe72c0f265da039a3d6fef?utm_source=gold_browser_extension

UIImage+UpFixed.swift

extension UIImage {
    func upFixedImage() -> UIImage? {
        // No-op if the orientation is already correct
        guard imageOrientation != .up else {
            return nil
        }
        
        var transform = CGAffineTransform.identity
        switch imageOrientation {
        case .down, .downMirrored:
            transform = transform.translatedBy(x: size.width, y: size.height)
            transform = transform.rotated(by: .pi)
        case .left, .leftMirrored:
            transform = transform.translatedBy(x: size.width, y: 0)
            transform = transform.rotated(by: .pi / 2)
        case .right, .rightMirrored:
            transform = transform.translatedBy(x: 0, y: size.height)
            transform = transform.rotated(by: -.pi / 2)
        default:
            break
        }
        
        switch imageOrientation {
        case .upMirrored, .downMirrored:
            transform = transform.translatedBy(x: size.width, y: 0)
            transform = transform.scaledBy(x: -1, y: 1)
        case .leftMirrored, .rightMirrored:
            transform = transform.translatedBy(x: size.height, y: 0)
            transform = transform.scaledBy(x: -1, y: 1)
        default:
            break
        }
        
        // Now we draw the underlying CGImage into a new context, applying the transform
        // calculated above.
        guard let cgImage = cgImage,
            let colorSpace = cgImage.colorSpace,
            let ctx = CGContext(data: nil, width: Int(size.width), height: Int(size.height),
                                bitsPerComponent: cgImage.bitsPerComponent,
                                bytesPerRow: 0, space: colorSpace, bitmapInfo: cgImage.bitmapInfo.rawValue) else {
            return nil
        }
        
        ctx.concatenate(transform)
        switch imageOrientation {
        case .left, .leftMirrored, .right, .rightMirrored:
            ctx.draw(cgImage, in: .init(origin: .zero, size: .init(width: size.height, height: size.width)))
        default:
            ctx.draw(cgImage, in: .init(origin: .zero, size: size))
        }
        
        // And now we just create a new UIImage from the drawing context
        guard let ref = ctx.makeImage() else {
            return nil
        }
        
        return UIImage(cgImage: ref)
    }
}