从照片中提取GPS数据

Question

我很难,因为我想从照片中提取GPS坐标.我使用该函数imagePickerController:didFinishPickingMediaWithInfo来选择图像,我使用新的Photos框架将该图像插入到collectionView中.我想从照片中提取GPS坐标.我做了一些研究,我知道UIImage不包含所有元数据,所以我尝试使用该AssetsLibrary框架.在里面didFinishPickingMediaWithInfo我使用以下代码来提取照片位置:

    var referenceURL : NSURL = info.objectForKey(UIImagePickerControllerReferenceURL) as NSURL
    var library : ALAssetsLibrary = ALAssetsLibrary()
    library.assetForURL(referenceURL, resultBlock: { (asset : ALAsset!) -> Void in
        var rep : ALAssetRepresentation = asset.defaultRepresentation()
        var metadata : NSDictionary = rep.metadata()


        let location: AnyObject! = asset.valueForProperty(ALAssetPropertyLocation)
        if location != nil {
            println(location)
        }
        else
        {
            println("Location not found")
        }


         })
    {
            (error : NSError!) -> Void in
    }

但是,它找不到位置,即使我检查了图像并且它包含EXIF元数据(它还包含我感兴趣的GPS位置).如何从照片中检索坐标？

Answer 1

ALAssetsLibrary在iOS 10中已弃用.幸运的是,使用Photos框架,实现起来很简单.当imagePickerController(_ picker:, didFinishPickingMediaWithInfo)被调用时,您可以检索通过简单的查询位置信息.看看下面的代码:

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
   if let URL = info[UIImagePickerControllerReferenceURL] as? URL {
       let opts = PHFetchOptions()
       opts.fetchLimit = 1
       let assets = PHAsset.fetchAssets(withALAssetURLs: [URL], options: opts)
       let asset = assets[0]
       // The location is "asset.location", as a CLLocation 

// ... Other stuff like dismiss omitted
}

希望这可以帮助.这是Swift 3,当然..

Answer 2

我找到了使用以下代码的解决方案:

 if picker.sourceType == UIImagePickerControllerSourceType.PhotoLibrary
    {
        if let currentLat = pickedLat as CLLocationDegrees?
        {
            self.latitude = pickedLat!
            self.longitude = pickedLong!
        }
        else
        {
        var library = ALAssetsLibrary()
        library.enumerateGroupsWithTypes(ALAssetsGroupAll, usingBlock: { (group, stop) -> Void in
                if (group != nil) {

                println("Group is not nil")
                println(group.valueForProperty(ALAssetsGroupPropertyName))
                group.enumerateAssetsUsingBlock { (asset, index, stop) in
                    if asset != nil
                    {
                    if let location: CLLocation = asset.valueForProperty(ALAssetPropertyLocation) as CLLocation!
                    { let lat = location.coordinate.latitude
                        let long = location.coordinate.longitude

                        self.latitude = lat
                        self.longitude = lat

                        println(lat)
                        println(long)
                        }
                    }
                }
            } else
                {
                println("The group is empty!")
                }
            })
            { (error) -> Void in
                println("problem loading albums: \(error)")
        }
    }
}

它的作用是,如果照片具有该属性,它会读取整个相册并打印位置,否则会打印"找不到位置".对于相册中的每张照片都这样做.所以我有另一个问题......我想显示我选择的照片的位置信息,而不是整张专辑.有没有人知道如何实现这一目标？