swift - 在 Swift 中将 GPS 元数据写入 EXIF

Question

我正在尝试将 gps 坐标写入在我的应用程序中拍摄的图像。所以我四处寻找要使用的代码，然后我编写了一个函数，它接受 Data 并返回 Data(因为我需要像这样将它发送到 Firebase.

但无论我如何编写此代码，元数据都不会“粘附”到图片上。图片在上传时看起来是正确的，但在下载时它包含的元数据不超过照片的大小。

我是不是完全错过了什么？

func setMetaData(imageData: Data) -> Data? {

    var source: CGImageSource? = nil
    source = CGImageSourceCreateWithData((imageData as CFData?)!, nil)
    let metadata = CGImageSourceCopyPropertiesAtIndex(source!, 0, nil) as? [AnyHashable: Any]
    var metadataAsMutable = metadata
    var EXIFDictionary = (metadataAsMutable?[(kCGImagePropertyExifDictionary as String)]) as? [AnyHashable: Any]
    var GPSDictionary = (metadataAsMutable?[(kCGImagePropertyGPSDictionary as String)]) as? [AnyHashable: Any]

    if !(EXIFDictionary != nil) {
        EXIFDictionary = [AnyHashable: Any]()
    }
    if !(GPSDictionary != nil) {
        GPSDictionary = [AnyHashable: Any]()
    }

    GPSDictionary![(kCGImagePropertyGPSLatitude as String)] = 30.21313
    GPSDictionary![(kCGImagePropertyGPSLongitude as String)] = 76.22346

    let dest_data = NSMutableData()
    guard let imageDest = CGImageDestinationCreateWithData(dest_data as CFMutableData, kUTTypeJPEG, 1, nil) else { return nil }
    CGImageDestinationAddImageFromSource(imageDest, source!, 0, (metadataAsMutable as CFDictionary?))


    if CGImageDestinationFinalize(imageDest) {

        return dest_data as Data
    } else {
        print("FAILED")
    }
    return nil
}

Answer 1

我找到了一个不太漂亮的解决方案，但它完全可以完成工作

func addMetaData(data: Data) -> NSData? {

    guard let source = CGImageSourceCreateWithData(data as CFData, nil) else {return nil}
    guard let type = CGImageSourceGetType(source) else {return nil}
    let mutableData = NSMutableData(data: data)
    guard let destination = CGImageDestinationCreateWithData(mutableData, type, 1, nil) else {
        return nil}

    guard let path = Bundle.main.url(forResource: "predict_pic", withExtension: "jpg") else {
        return nil }
    let imageSource = CGImageSourceCreateWithURL(path as CFURL, nil)
    let imageProperties = CGImageSourceCopyMetadataAtIndex(imageSource!, 0, nil)

    let mutableMetadata = CGImageMetadataCreateMutableCopy(imageProperties!)

    CGImageMetadataSetValueMatchingImageProperty(mutableMetadata!, kCGImagePropertyGPSDictionary, kCGImagePropertyGPSLatitudeRef, "N" as CFTypeRef)
    CGImageMetadataSetValueMatchingImageProperty(mutableMetadata!, kCGImagePropertyGPSDictionary, kCGImagePropertyGPSLatitude, location.coordinate.latitude as CFTypeRef)
    CGImageMetadataSetValueMatchingImageProperty(mutableMetadata!, kCGImagePropertyGPSDictionary, kCGImagePropertyGPSLongitudeRef, "E" as CFTypeRef)
    CGImageMetadataSetValueMatchingImageProperty(mutableMetadata!, kCGImagePropertyGPSDictionary, kCGImagePropertyGPSLongitude, location.coordinate.longitude as CFTypeRef)

    let finalMetadata:CGImageMetadata = mutableMetadata!
    CGImageDestinationAddImageAndMetadata(destination, UIImage(data: data)!.cgImage! , finalMetadata, nil)
    guard CGImageDestinationFinalize(destination) else { return nil }
    return mutableData;
}