A Swift class for extracting exif data from URL, UIImage or Data types 🔭

ExifData.swift

//
//  ExifData.swift
//  Qeepsake
//
//  Created by Luke Farrell on 26/05/2022.
//

import Foundation
import ImageIO

class ExifData: NSObject {
  var colorModel: String?;
  var pixelWidth: Double?;
  var pixelHeight: Double?;
  var dpiWidth: Int?;
  var dpiHeight: Int?;
  var depth: Int?;
  var orientation: Int?;
  var apertureValue: String?;
  var brightnessValue: String?;
  var dateTimeDigitized: String?;
  var dateTimeOriginal: String?;
  var offsetTime: String?;
  var offsetTimeDigitized: String?;
  var offsetTimeOriginal: String?;
  var model: String?;
  var software: String?;
  var tileLength: Double?;
  var tileWidth: Double?;
  var xResolution: Double?;
  var yResolution: Double?;
  var altitude: String?;
  var destBearing: String?;
  var hPositioningError: String?;
  var imgDirection: String?;
  var latitude: String?;
  var longitude: String?;
  var speed: Double?;
  
  private var dictionary: [String: Any] {
    return [
      "colorModel": colorModel as Any,
      "pixelWidth": pixelWidth as Any,
      "pixelHeight": pixelHeight as Any,
      "dpiWidth": dpiWidth as Any,
      "dpiHeight": dpiHeight as Any,
      "depth": depth as Any,
      "orientation": orientation as Any,
      "apertureValue": apertureValue as Any,
      "brightnessValue": brightnessValue as Any,
      "dateTimeDigitized": dateTimeDigitized as Any,
      "dateTimeOriginal": dateTimeOriginal as Any,
      "offsetTime": offsetTime as Any,
      "offsetTimeDigitized": offsetTimeDigitized as Any,
      "offsetTimeOriginal": offsetTimeOriginal as Any,
      "model": model as Any,
      "software": software as Any,
      "tileLength": tileLength as Any,
      "tileWidth": tileWidth as Any,
      "xResolution": xResolution as Any,
      "yResolution": yResolution as Any,
      "altitude": altitude as Any,
      "destBearing": destBearing as Any,
      "hPositioningError": hPositioningError as Any,
      "imgDirection": imgDirection as Any,
      "latitude": latitude as Any,
      "longitude": longitude as Any,
      "speed": speed as Any
    ]
  }
  
  public var toDictionary: NSDictionary {
    return dictionary as NSDictionary;
  }
  
  init(data: Data) {
    super.init();
    self.setExifData(data: data as CFData);
  }

  init(url: URL) {
    super.init();
    
    if let data = NSData(contentsOf: url) {
      self.setExifData(data: data);
    }
  }
  
  init(image: UIImage) {
    super.init();
    
    if let data = image.cgImage?.dataProvider?.data {
      self.setExifData(data: data);
    }
  }
  
  func setExifData(data: CFData) {
    let options = [kCGImageSourceShouldCache as String: kCFBooleanFalse];
    
    if let imgSrc = CGImageSourceCreateWithData(data, options as CFDictionary) {
      if let metadata = CGImageSourceCopyPropertiesAtIndex(imgSrc, 0, options as CFDictionary) as? NSDictionary {
        self.colorModel = metadata[kCGImagePropertyColorModel] as? String;
        self.pixelWidth = metadata[kCGImagePropertyPixelWidth] as? Double;
        self.pixelHeight = metadata[kCGImagePropertyPixelHeight] as? Double;
        self.dpiWidth = metadata[kCGImagePropertyDPIWidth] as? Int;
        self.dpiHeight = metadata[kCGImagePropertyDPIHeight] as? Int;
        self.depth = metadata[kCGImagePropertyDepth] as? Int;
        self.orientation = metadata[kCGImagePropertyOrientation] as? Int;
        
        if let tiffData = metadata[kCGImagePropertyTIFFDictionary] as? NSDictionary {
          self.model = tiffData[kCGImagePropertyTIFFModel] as? String;
          self.software = tiffData[kCGImagePropertyTIFFSoftware] as? String;
          self.tileLength = tiffData[kCGImagePropertyTIFFTileLength] as? Double;
          self.tileWidth = tiffData[kCGImagePropertyTIFFTileWidth] as? Double;
          self.xResolution = tiffData[kCGImagePropertyTIFFXResolution] as? Double;
          self.yResolution = tiffData[kCGImagePropertyTIFFYResolution] as? Double;
        }
        
        if let exifData = metadata[kCGImagePropertyExifDictionary] as? NSDictionary {
          self.apertureValue = exifData[kCGImagePropertyExifApertureValue] as? String;
          self.brightnessValue = exifData[kCGImagePropertyExifBrightnessValue] as? String;
          self.dateTimeDigitized = exifData[kCGImagePropertyExifDateTimeDigitized] as? String;
          self.dateTimeOriginal = exifData[kCGImagePropertyExifDateTimeOriginal] as? String;
          if #available(iOS 13.0, *) {
            self.offsetTime = exifData[kCGImagePropertyExifOffsetTime] as? String
            self.offsetTimeDigitized = exifData[kCGImagePropertyExifOffsetTimeDigitized] as? String;
            self.offsetTimeOriginal = exifData[kCGImagePropertyExifOffsetTimeOriginal] as? String;
          } else {
            // Fallback on earlier versions
          };
        }
        
        if let gpsData = metadata[kCGImagePropertyGPSDictionary] as? NSDictionary {
          self.altitude = gpsData[kCGImagePropertyGPSAltitude] as? String;
          self.destBearing = gpsData[kCGImagePropertyGPSDestBearing] as? String;
          self.hPositioningError = gpsData[kCGImagePropertyGPSHPositioningError] as? String;
          self.imgDirection = gpsData[kCGImagePropertyGPSImgDirection] as? String;
          self.latitude = gpsData[kCGImagePropertyGPSLatitude] as? String;
          self.longitude = gpsData[kCGImagePropertyGPSLongitude] as? String;
          self.speed = gpsData[kCGImagePropertyGPSSpeed] as? Double;
        }
      }
    }
  }
}

First, nice writeup of the picker exif issue!

I was just wondering why you opted for an NSObject for ExifData. Wouldn't even a struct be perfect here?

@nidegen Thanks! :) my swift is pretty rusty, what are the advantages to using a struct?

I see. No big advantages. Classes are reference types, structs are value types, so have a little less overhead. Also, inheriting from `NSObject` is only used for classes that make use of some older objective C APIs. In the end is not a big deal, I was just wondering if I had missed a specific reason why it was not just a struct:)

…

On 5 Dec 2022, at 16:32, Luke Brandon Farrell ***@***.***> wrote: @lukebrandonfarrell commented on this gist. @nidegen <https://github.com/nidegen> Thanks! :) my swift is pretty rusty, what are the advantages to using a struct? — Reply to this email directly, view it on GitHub <https://gist.github.com/961a6dbc8367f0ac9cabc89b0052d1fe#gistcomment-4392270> or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACC7NHZOOZF755SQWKAN7DDWLYDJDBFKMF2HI4TJMJ2XIZLTSKBKK5TBNR2WLJDHNFZXJJDOMFWWLK3UNBZGKYLEL52HS4DFQKSXMYLMOVS2I5DSOVS2I3TBNVS3W5DIOJSWCZC7OBQXE5DJMNUXAYLOORPWCY3UNF3GS5DZVRZXKYTKMVRXIX3UPFYGLK2HNFZXIQ3PNVWWK3TUUZ2G64DJMNZZDAVEOR4XAZNEM5UXG5FFOZQWY5LFVEYTCNRXGMZDCOBZU52HE2LHM5SXFJTDOJSWC5DF>. You are receiving this email because you were mentioned. Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

No specific reason, I think it makes sense to be a struct tbh, you are right. When I get into this code again, which I will do soon as I am working on a library using this Gist. I can update it, thanks for pointing it out! :)

Thanks for sharing this, it is so helpful. Just wanna let you know that we have to swap the Width and Height when the orientation is Portrait.

@jmarkstar Interesting! How does that look in practice? Could you share a code snippet?

I think you forgot the import UIKit. But really handy thank you!

@celian-m Very possible yes! You welcome :)