我正在尝试从图像样本缓冲区中将一些元数据与图像一起保存。
我需要:
我尝试从数据创建UIImage,但这会剥夺元数据。我尝试使用数据中的CIImage保留元数据,但无法旋转它,然后将其保存到文件中。
private func snapPhoto(success: (UIImage, CFMutableDictionary) -> Void, errorMessage: String -> Void) { guard !self.stillImageOutput.capturingStillImage, let videoConnection = stillImageOutput.connectionWithMediaType(AVMediaTypeVideo) else { return } videoConnection.fixVideoOrientation() stillImageOutput.captureStillImageAsynchronouslyFromConnection(videoConnection) { (imageDataSampleBuffer, error) -> Void in guard imageDataSampleBuffer != nil && error == nil else { errorMessage("Couldn't snap photo") return } let data = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageDataSampleBuffer) let metadata = CMCopyDictionaryOfAttachments(nil, imageDataSampleBuffer, CMAttachmentMode(kCMAttachmentMode_ShouldPropagate)) let metadataMutable = CFDictionaryCreateMutableCopy(nil, 0, metadata) let utcDate = "\(NSDate())" let cfUTCDate = CFStringCreateCopy(nil, utcDate) CFDictionarySetValue(metadataMutable!, unsafeAddressOf(kCGImagePropertyGPSDateStamp), unsafeAddressOf(cfUTCDate)) guard let image = UIImage(data: data)?.fixOrientation() else { return } CFDictionarySetValue(metadataMutable, unsafeAddressOf(kCGImagePropertyOrientation), unsafeAddressOf(1)) success(image, metadataMutable) } }
这是我保存图像的代码。
func saveImageAsJpg(image: UIImage, metadata: CFMutableDictionary) { // Add metadata to image guard let jpgData = UIImageJPEGRepresentation(image, 1) else { return } jpgData.writeToFile("\(self.documentsDirectory)/image1.jpg", atomically: true) }
最后,我弄清楚了如何使所有东西按我需要的方式工作。对我最大的帮助是发现可以将CFDictionary转换为NSMutableDictionary。
这是我的最终代码:
如您所见,我向EXIF字典中添加了一个属性,用于数字化日期,并更改了方向值。
private func snapPhoto(success: (UIImage, NSMutableDictionary) -> Void, errorMessage: String -> Void) { guard !self.stillImageOutput.capturingStillImage, let videoConnection = stillImageOutput.connectionWithMediaType(AVMediaTypeVideo) else { return } videoConnection.fixVideoOrientation() stillImageOutput.captureStillImageAsynchronouslyFromConnection(videoConnection) { (imageDataSampleBuffer, error) -> Void in guard imageDataSampleBuffer != nil && error == nil else { errorMessage("Couldn't snap photo") return } let data = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageDataSampleBuffer) let rawMetadata = CMCopyDictionaryOfAttachments(nil, imageDataSampleBuffer, CMAttachmentMode(kCMAttachmentMode_ShouldPropagate)) let metadata = CFDictionaryCreateMutableCopy(nil, 0, rawMetadata) as NSMutableDictionary let exifData = metadata.valueForKey(kCGImagePropertyExifDictionary as String) as? NSMutableDictionary exifData?.setValue(NSDate().toString("yyyy:MM:dd HH:mm:ss"), forKey: kCGImagePropertyExifDateTimeDigitized as String) metadata.setValue(exifData, forKey: kCGImagePropertyExifDictionary as String) metadata.setValue(1, forKey: kCGImagePropertyOrientation as String) guard let image = UIImage(data: data)?.fixOrientation() else { errorMessage("Couldn't create image") return } success(image, metadata) } }
还有我用于保存带有元数据的图像的最终代码:
我讨厌很多警卫声明,但这比强制展开要好。
func saveImage(withMetadata image: UIImage, metadata: NSMutableDictionary) { let filePath = "\(self.documentsPath)/image1.jpg" guard let jpgData = UIImageJPEGRepresentation(image, 1) else { return } // Add metadata to jpgData guard let source = CGImageSourceCreateWithData(jpgData, nil), let uniformTypeIdentifier = CGImageSourceGetType(source) else { return } let finalData = NSMutableData(data: jpgData) guard let destination = CGImageDestinationCreateWithData(finalData, uniformTypeIdentifier, 1, nil) else { return } CGImageDestinationAddImageFromSource(destination, source, 0, metadata) guard CGImageDestinationFinalize(destination) else { return } // Save image that now has metadata self.fileService.save(filePath, data: finalData) }
这是我的更新save方法(与我编写此问题时使用的方法不完全相同,因为我已更新到Swift 2.3,但概念相同):
save
public func save(fileAt path: NSURL, with data: NSData) throws -> Bool { guard let pathString = path.absoluteString else { return false } let directory = (pathString as NSString).stringByDeletingLastPathComponent if !self.fileManager.fileExistsAtPath(directory) { try self.makeDirectory(at: NSURL(string: directory)!) } if self.fileManager.fileExistsAtPath(pathString) { try self.delete(fileAt: path) } return self.fileManager.createFileAtPath(pathString, contents: data, attributes: [NSFileProtectionKey: NSFileProtectionComplete]) }