Swift PNG Image being saved with incorrect orientation

问题

If I use the image before it is saved it is normal. But if I save it and use it later is is 90 degrees turned. How can I make sure it doesn\'t save sideways?

func saveEvent(_ center1: CLLocation, title2: String, imagePicked1: UIImage)
    {
        let data = UIImagePNGRepresentation(imagePicked1);///
        let url = NSURL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(NSUUID().uuidString+\".dat\")
        do {
            try data!.write(to: url!, options: [])
        } catch let e as NSError {
            print(\"Error! \\(e)\");
            return
        }
        let image11 = CKAsset(fileURL: url!)

        self.eventRecord.setObject(image11 as CKAsset, forKey: \"Picture\")
        let publicData = CKContainer.default().publicCloudDatabase
            publicData.save(self.eventRecord, completionHandler: { record, error in
                if error == nil
                {
                    print(\"Image saved\")
                }else{
                    print(error!)
                }
        })
    }

回答1:

If you need to save your PNG with correct rotation you will need to redraw your image if its orientation it is not .up. You can redraw it as follow:

extension UIImage {
    var png: Data? {
        guard let flattened = flattened else { return nil }
        return flattened.pngData()  // Swift 4.2 or later
        // return UIImagePNGRepresentation(flattened)  // Swift 4.1  or earlier
    }
    var flattened: UIImage? {
        if imageOrientation == .up { return self }
        UIGraphicsBeginImageContextWithOptions(size, false, scale)
        defer { UIGraphicsEndImageContext() }
        draw(in: CGRect(origin: .zero, size: size))
        return UIGraphicsGetImageFromCurrentImageContext()
    }
}

edit/update:

For iOS10+ tvOS10+ you can use UIGraphicsImageRenderer:

extension UIImage {
    var png: Data? {
        return flattened.pngData()
    }
    var flattened: UIImage {
        if imageOrientation == .up { return self }
        return UIGraphicsImageRenderer(size: size, format: imageRendererFormat).image { _ in draw(at: .zero) }
    }
}

---

let image = UIImage(data: try! Data(contentsOf: URL(string: "https://i.stack.imgur.com/varL9.jpg")!))!
if let data = image.png {
    let imageFromPNGData = UIImage(data: data)
}

来源：https://stackoverflow.com/questions/42098390/swift-png-image-being-saved-with-incorrect-orientation