ios – Swift：自定义相机使用图像保存修改后的元数据

我试图保存图像样本缓冲区中的一些元数据以及图像.

我需要：

>将图像旋转到元数据的方向
>从元数据中删除方向
>将日期保存到元数据中
>将包含元数据的图像保存到文档目录

我试过从数据创建一个UIImage,但是删除了元数据.我已经尝试使用数据中的CIImage来保存元数据,但是我无法将其旋转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,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)
}

解决方法

我最终弄清楚如何让一切按照我需要的方式工作.对我帮助最大的事情是发现CFDictionary可以作为NSMutableDictionary投射.

这是我的最终代码：

如您所见,我在EXIF词典中为数字化日期添加了一个属性,并更改了方向值.

private func snapPhoto(success: (UIImage,NSMutableDictionary) -> Void,error) -> Void in
        guard imageDataSampleBuffer != nil && error == nil else {
            errorMessage("Couldn't snap photo")
            return
        }

        let data = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageDataSampleBuffer)

        let rawMetadata = CMCopyDictionaryOfAttachments(nil,CMAttachmentMode(kCMAttachmentMode_ShouldPropagate))
        let metadata = CFDictionaryCreateMutableCopy(nil,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)
    }
}

以及使用元数据保存图像的最终代码：

很多防守声明,我讨厌,但它比强行解缠更好.

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,metadata)
    guard CGImageDestinationFinalize(destination) else { return }

    // Save image that now has metadata
    self.fileService.save(filePath,data: finalData)
}

这是我更新的保存方法(与我在编写此问题时使用的完全相同,因为我已更新到Swift 2.3,但概念是相同的)：

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])
}