访问 swift 中的 EXIF 数据

Question

我尝试使用此示例代码访问 Exif 数据：

let fileextension = NSURL(fileURLWithPath: mDir + "/" + f).pathExtension

            if fileextension == "PSD" || fileextension == "NEF" || fileextension == "3FR" || fileextension == "CR2" || fileextension == "DNG" || fileextension == "JPEG" || fileextension == "JPG" || fileextension == "PSB" || fileextension == "RAF" || fileextension == "TIF" {

                let fileattr = try fileManager.attributesOfItem(atPath: mDir + "/" + f)
                let filesize = fileattr[FileAttributeKey.size] as! Int64

                let UrlPath = URL(fileURLWithPath: mDir + "/" + f)
                let imageSource = CGImageSourceCreateWithURL(UrlPath as CFURL, nil)
                let result = CGImageSourceCopyMetadataAtIndex(imageSource!, 0, nil)
                let d = result as! [AnyHashable:Any]
                let tiffDict = d["{TIFF}"] as! [AnyHashable:Any]
                let filedate = tiffDict["DateTime"] as! Date

我有这个错误：

Could not cast value of type '__NSCFType' (0x7fff89750188) to 'NSDictionary' (0x7fff89750fe8).

但是这个示例代码可以在 playground 中运行。

有什么解释吗？

Answer 1

要回答实际问题 ;)，看起来您调用了错误的函数来直接将其作为字典获取，而不是使用 CGImageSourceCopyMetadataAtIndex 复制元数据，而使用 CGImageSourceCopyPropertiesAtIndex 代替

if let props = CGImageSourceCopyPropertiesAtIndex(imageSource!, 0, nil) as? [String: Any], 
   let tiffData = props["{TIFF}"] {
    print(tiffData)
}

原回答

我使用 CGImageMetadataCopyTags 将元数据提取为数组，然后使用 CGImageMetadataTagCopyName 和 CGImageMetadataTagCopyValue 将数据映射到 swift 字典中

let extensions = ["PSD",  "NEF",  "3FR",  "CR2",  "DNG",  "JPEG",  "JPG",  "PSB",  "RAF",  "TIF"]
let fileManager = FileManager.default
let url = URL(fileURLWithPath: mDir + "/" + f)

var metaData = [String: Any]()
if extensions.contains(url.pathExtension) {
    let imageSource = CGImageSourceCreateWithURL(url as CFURL, nil)
    if let result = CGImageSourceCopyMetadataAtIndex(imageSource!, 0, nil) {
        if let array = CGImageMetadataCopyTags(result) as? [CGImageMetadataTag] {
            metaData = array.reduce(into: [String: Any]()) {
                guard let name = CGImageMetadataTagCopyName(),
                    let value = CGImageMetadataTagCopyValue()
                else {
                    return
                }
                [=11=][String(name)] = value
            }
        }
    }
}

请注意，这只给出了像 "ShutterSpeedValue" 这样的标签名称，为了包括像 "exif"、"tiff"、"xmp" 这样的标签类型，我们还可以得到前缀:

guard let prefix = CGImageMetadataTagCopyPrefix(), 
      let name = CGImageMetadataTagCopyName(),
      let value = CGImageMetadataTagCopyValue()
else { return }

[=12=]["\(prefix):\(name)"] = value

访问 swift 中的 EXIF 数据

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