Swift accessing EXIF Dictionary - ios

Question

Info: Using Swift and the CGImageSourceCreateWithURL function.
I am attempting to load a file from a URL and then edit a dictionary which has all the data from that particular photo.
This is the code from the .swift file.
let url = NSURL(string: "http://jwphotographic.co.uk/Images/1.jpg")
let imageSource = CGImageSourceCreateWithURL(url, nil)
let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil) as Dictionary
println(imageProperties)
//this is an example
let aperture = imageProperties[kCGImagePropertyGPSLatitude] as! NSNumber!
/*
//these are all being defined as nil
//Load the ones from the exif data of the file
let lensUsed = imageProperties[kCGImagePropertyExifFocalLength]
let aperture = imageProperties[kCGImagePropertyExifApertureValue] as!
let isoSpeed = imageProperties[kCGImagePropertyExifISOSpeedRatings] as! NSNumber
let latitude = imageProperties[kCGImagePropertyGPSLatitude] as! NSNumber
let longitude = imageProperties[kCGImagePropertyGPSLongitude] as! NSNumber
let shutterSpeed = imageProperties[kCGImagePropertyExifShutterSpeedValue] as! NSNumber
let cameraName = imageProperties[kCGImagePropertyExifBodySerialNumber] as! NSNumber
*/
println(aperture)
Even though image properties prints all the data as would be expected, no-matter what I have attmpted to extract from the imageProperties dictionary - it is always returned as null - such as 'aperture' in the example. The imageProperties prints as;
[{TIFF}: {
Artist = JOHN;
Copyright = "johnrwatson0#gmail.com";
DateTime = "2015:07:31 21:07:05";
Make = Canon;
Model = "Canon EOS 7D Mark II";
ResolutionUnit = 2;
Software = "Adobe Photoshop Lightroom 6.0 (Macintosh)";
XResolution = 72;
YResolution = 72;
}, {IPTC}: {
Byline = (
JOHN
);
CopyrightNotice = etc.. etc..
I have done a lot of research and testing and I simply cannot work out what I'm doing wrong to access the elements in this dictionary - Could someone give me an example how I would set a variable as the "Model" element inside the dictionary?

Answer 1

In Swift 3.0 I found the following solution
let url = NSURL(string: "http://jwphotographic.co.uk/Images/1.jpg")
let imageSource = CGImageSourceCreateWithURL(url, nil)
let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil) as Dictionary?
let exifDict = imageProperties?[kCGImagePropertyExifDictionary]
Now you can access the exif-Tags by for example
let dateTimeOriginal = exifDict?[kCGImagePropertyExifDateTimeOriginal]
Swift.print("dateTimeOriginal: \(dateTimeOriginal)")
You will get optional values and you have to test, if there are values or nil. For a list of available property constants look at the apple documentation.

Answer 2

To get to Exif parameters do the following:
let filePath_ = "file:///Users/pfernandes/Documents/softwareDevelopment/PhotoLine/TestData/IMG_1243.JPG"
let fileURL = NSURL(string:filePath_)
let myImage = CGImageSourceCreateWithURL(fileURL!,nil)
let imageDict = CGImageSourceCopyPropertiesAtIndex(myImage!, 0, nil)! as NSDictionary;
let tiffModel_ = imageDict.value(forKey: "{TIFF}")
let cameraMake = (tiffModel_ as AnyObject).value(forKey: kCGImagePropertyTIFFMake as String)
let cameraModel = (tiffModel_ as AnyObject).value(forKey: kCGImagePropertyTIFFModel as String)
let exifDict_ = imageDict.value(forKey: "{Exif}") as! NSDictionary
let dateTimeOriginal = exifDict_.value(forKey:kCGImagePropertyExifDateTimeOriginal as String) as! NSString
let exposure = exifDict_.value(forKey:kCGImagePropertyExifExposureTime as String)
print ("\(String(describing: cameraMake)) \(String(describing: cameraModel)) \(dateTimeOriginal) \(exposure!)")

Answer 3

This code will help you to obtain the date of the photo and exif
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
picker.dismiss(animated: true, completion: nil)
if let image = info[.originalImage] as? UIImage {
let assetURL = info[UIImagePickerController.InfoKey.referenceURL] as! NSURL
let asset = PHAsset.fetchAssets(withALAssetURLs: [assetURL as URL], options: nil)
guard let result = asset.firstObject else {
return
}
let imageManager = PHImageManager.default()
imageManager.requestImageData(for: result , options: nil, resultHandler:{
(data, responseString, imageOriet, info) -> Void in
let imageData: NSData = data! as NSData
if let imageSource = CGImageSourceCreateWithData(imageData, nil) {
let imageDict = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil)! as NSDictionary
let exifDict_ = imageDict.value(forKey: "{Exif}") as! NSDictionary
let dateTimeOriginal = exifDict_.value(forKey:kCGImagePropertyExifDateTimeOriginal as String) as! NSString
print (" exifDict : \(exifDict_)")
print (" fecha : original \(dateTimeOriginal)")
}
})
picker.dismiss(animated: true, completion: nil)
}

Answer 4

Here is a sample code that helps us in reading the entire imageMetadata and converts it into dictionary format.
guard let imageSource = CGImageSourceCreateWithURL(fileURL as CFURL, nil),
let metadata = CGImageSourceCopyMetadataAtIndex(imageSource, 0, nil),
let tags = CGImageMetadataCopyTags(metadata),
let imageInfo = self.readMetadataTagArr(tagArr: tags) else { return }
Then there are a few helper functions that actually do all the hardwork to extract/convert the data into dictionary format.
/// Reads the Arrays of tags and convert them into a dictionary of [String: Any]
private static func readMetadataTagArr(tagArr: CFArray) -> [String: Any]? {
var result = [String: Any]()
for (_, tag) in (tagArr as NSArray).enumerated() {
let tagMetadata = tag as! CGImageMetadataTag
if let cfName = CGImageMetadataTagCopyName(tagMetadata) {
let name = String(cfName)
result[name] = self.readMetadataTag(metadataTag: tagMetadata)
}
}
return result
}
/// convert CGImageMetadataTag to a dictionary of [String: Any]
private static func readMetadataTag(metadataTag: CGImageMetadataTag) -> [String: Any] {
var result = [String: Any]()
guard let cfName = CGImageMetadataTagCopyName(metadataTag) else { return result }
let name = String(cfName)
let value = CGImageMetadataTagCopyValue(metadataTag)
/// checking the type of `value` object and then performing respective operation on `value`
if CFGetTypeID(value) == CFStringGetTypeID() {
let valueStr = String(value as! CFString)
result[name] = valueStr
} else if CFGetTypeID(value) == CFDictionaryGetTypeID() {
let nsDict: NSDictionary = value as! CFDictionary
result[name] = self.getDictionary(from: nsDict)
} else if CFGetTypeID(value) == CFArrayGetTypeID() {
let valueArr: NSArray = value as! CFArray
for (_, item) in valueArr.enumerated() {
let tagMetadata = item as! CGImageMetadataTag
result[name] = self.readMetadataTag(metadataTag: tagMetadata)
}
} else {
// when the data was of some other type
let descriptionString: CFString = CFCopyDescription(value);
let str = String(descriptionString)
result[name] = str
}
return result
}
/// Converting CGImage Metadata dictionary to [String: Any]
private static func getDictionary(from nsDict: NSDictionary) -> [String: Any] {
var subDictionary = [String: Any]()
for (key, val) in nsDict {
guard let key = key as? String else { continue }
let tempDict: [String: Any] = [key: val]
if JSONSerialization.isValidJSONObject(tempDict) {
subDictionary[key] = val
} else {
let mData = val as! CGImageMetadataTag
let tempDict: [String: Any] = [key: self.readMetadataTag(metadataTag: mData)]
if JSONSerialization.isValidJSONObject(tempDict) {
subDictionary[key] = tempDict
}
}
}
return subDictionary
}
Here is the list of all dictionary keys extracted
Here are some sample dictionary values