在 iOS4.1 上保存带有照片的地理标记信息答案

【问题标题】：Saving Geotag info with photo on iOS4.1在 iOS4.1 上保存带有照片的地理标记信息
【发布时间】：2011-04-22 11:51:54
【问题描述】：

我在尝试在 iOS4.1 上使用地理标签信息将照片保存到相机胶卷时遇到重大问题。我正在使用以下 ALAssetsLibrary API：

- (void)writeImageDataToSavedPhotosAlbum:(NSData *)imageData 
                                metadata:(NSDictionary *)metadata 
                         completionBlock:(ALAssetsLibraryWriteImageCompletionBlock)completionBlock

我有 GPS 坐标，我希望将照片保存为输入。不幸的是，没有文档或示例代码描述如何形成封装 GPS 坐标的元数据 NSDictionary。有人可以发布一个已知有效的示例代码吗？

我也尝试使用 iPhone Exif 库将地理信息保存在 imageData 中，而不是使用元数据，但不幸的是 iPhone Exif 库正在崩溃。非常感谢任何帮助。

【问题讨论】：

标签： iphone cocoa-touch ios4 assetslibrary

【解决方案1】：

以下代码可将 CLLocation 对象中的所有可用信息复制为 GPS 元数据字典的正确格式：

- (NSDictionary *)getGPSDictionaryForLocation:(CLLocation *)location {
    NSMutableDictionary *gps = [NSMutableDictionary dictionary];

    // GPS tag version
    [gps setObject:@"2.2.0.0" forKey:(NSString *)kCGImagePropertyGPSVersion];

    // Time and date must be provided as strings, not as an NSDate object
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"HH:mm:ss.SSSSSS"];
    [formatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];
    [gps setObject:[formatter stringFromDate:location.timestamp] forKey:(NSString *)kCGImagePropertyGPSTimeStamp];
    [formatter setDateFormat:@"yyyy:MM:dd"];
    [gps setObject:[formatter stringFromDate:location.timestamp] forKey:(NSString *)kCGImagePropertyGPSDateStamp];
    [formatter release];

    // Latitude
    CGFloat latitude = location.coordinate.latitude;
    if (latitude < 0) {
        latitude = -latitude;
        [gps setObject:@"S" forKey:(NSString *)kCGImagePropertyGPSLatitudeRef];
    } else {
        [gps setObject:@"N" forKey:(NSString *)kCGImagePropertyGPSLatitudeRef];
    }
    [gps setObject:[NSNumber numberWithFloat:latitude] forKey:(NSString *)kCGImagePropertyGPSLatitude];

    // Longitude
    CGFloat longitude = location.coordinate.longitude;
    if (longitude < 0) {
        longitude = -longitude;
        [gps setObject:@"W" forKey:(NSString *)kCGImagePropertyGPSLongitudeRef];
    } else {
        [gps setObject:@"E" forKey:(NSString *)kCGImagePropertyGPSLongitudeRef];
    }
    [gps setObject:[NSNumber numberWithFloat:longitude] forKey:(NSString *)kCGImagePropertyGPSLongitude];

    // Altitude
    CGFloat altitude = location.altitude;
    if (!isnan(altitude)){
        if (altitude < 0) {
            altitude = -altitude;
            [gps setObject:@"1" forKey:(NSString *)kCGImagePropertyGPSAltitudeRef];
        } else {
            [gps setObject:@"0" forKey:(NSString *)kCGImagePropertyGPSAltitudeRef];
        }
        [gps setObject:[NSNumber numberWithFloat:altitude] forKey:(NSString *)kCGImagePropertyGPSAltitude];
    }

    // Speed, must be converted from m/s to km/h
    if (location.speed >= 0){
        [gps setObject:@"K" forKey:(NSString *)kCGImagePropertyGPSSpeedRef];
        [gps setObject:[NSNumber numberWithFloat:location.speed*3.6] forKey:(NSString *)kCGImagePropertyGPSSpeed];
    }

    // Heading
    if (location.course >= 0){
        [gps setObject:@"T" forKey:(NSString *)kCGImagePropertyGPSTrackRef];
        [gps setObject:[NSNumber numberWithFloat:location.course] forKey:(NSString *)kCGImagePropertyGPSTrack];
    }

    return gps;
}

将此方法返回的字典指定为您传递给writeImageDataToSavedPhotosAlbum:metadata:completionBlock: 或CGImageDestinationAddImage() 的元数据字典中kCGImagePropertyGPSDictionary 键的值。

【讨论】：

我认为你应该使用 Double 而不是 Float 的经纬度......否则你可能会离开几英尺/米。
@Anomie ，谈到 kCGImagePropertyGPSDateStamp 和 kCGImagePropertyGPSTimeStamp ，是否可以添加我们自己的日期/时间。而不是从“location.timestamp”中获取。？
@ShishirShetty：你可以伪造任何一点的地理位置数据，如果你想做的话。
[gps setObject:@"0" forKey:(NSString *) kCGImagePropertyGPSAltitudeRef] 不起作用。它必须是[gps setObject:[NSNumber numberWithInt:1] forKey:(NSString *)kCGImagePropertyGPSAltitudeRef];
再次感谢您。我稍微清理了您的代码并将其发布为 Gist：gist.github.com/rsattar/b06060df7ea293b398d1

【解决方案2】：

我使用此代码并创建了一个 NSMutableDictionary 来帮助将地理标记和其他元数据保存到图像中。在这里查看我的博文：

http://blog.codecropper.com/2011/05/adding-metadata-to-ios-images-the-easy-way/

【讨论】：

【解决方案3】：

经过大量搜索，我找到并改编了这个

这会将 cclocation 数据转换为合适的 NSDictionary

 #import <ImageIO/ImageIO.h>

+(NSMutableDictionary *)updateExif:(CLLocation *)currentLocation{


    NSMutableDictionary* locDict = [[NSMutableDictionary alloc] init];


    CLLocationDegrees exifLatitude = currentLocation.coordinate.latitude;
    CLLocationDegrees exifLongitude = currentLocation.coordinate.longitude;

    [locDict setObject:currentLocation.timestamp forKey:(NSString*)kCGImagePropertyGPSTimeStamp];

    if (exifLatitude <0.0){
        exifLatitude = exifLatitude*(-1);
        [locDict setObject:@"S" forKey:(NSString*)kCGImagePropertyGPSLatitudeRef];
    }else{
        [locDict setObject:@"N" forKey:(NSString*)kCGImagePropertyGPSLatitudeRef];
    }
    [locDict setObject:[NSNumber numberWithFloat:exifLatitude] forKey:(NSString*)kCGImagePropertyGPSLatitude];

    if (exifLongitude <0.0){
        exifLongitude=exifLongitude*(-1);
        [locDict setObject:@"W" forKey:(NSString*)kCGImagePropertyGPSLongitudeRef];
    }else{
        [locDict setObject:@"E" forKey:(NSString*)kCGImagePropertyGPSLongitudeRef];
    }
    [locDict setObject:[NSNumber numberWithFloat:exifLongitude] forKey:(NSString*) kCGImagePropertyGPSLongitude];


    return [locDict autorelease];

}

然后我将它添加到您通过相机获得的现有元数据中（默认情况下没有 GPS 数据）

我得到这样的原始元数据

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{  
    [imageMetaData setDictionary:[[info objectForKey:UIImagePickerControllerMediaMetadata] copy]];
}

然后我添加上一个方法生成的 gps 字典。

[imageMetaData setObject:currentLocation forKey:(NSString*)kCGImagePropertyGPSDictionary];          

    [library writeImageToSavedPhotosAlbum:[viewImage CGImage] metadata:imageMetaData completionBlock:photoCompblock];

【讨论】：

好答案，+1，但您设置 kCGImagePropertyGPSTimeStamp 错误。该值必须是 NSString 而不是 NSDate。
你不需要copy作为UIImagePickerControllerMediaMetadata对象的字典；告诉可变字典将自己设置为匹配另一个字典将修改接收字典，以便字典成为副本。您使用copy 消息制作的副本被浪费了；更糟糕的是，既然你不释放它，你就会泄露它。您可以通过释放或自动释放它来解决这个问题，但最好不要一开始就制作不必要的副本。

【解决方案4】：

这里有一个方便的 CLLocation 类别，可以为您完成所有这些工作：

https://gist.github.com/phildow/6043486

【讨论】：

【解决方案5】：

Anomie 在 Swift 4.0 中的响应：

func getGPSDictionaryForLocation(location:CLLocation) -> [String:AnyObject] {

    var gps = [String:AnyObject]()

    var latitude = location.coordinate.latitude

    if(latitude < 0){
        latitude = -latitude
        gps[kCGImagePropertyGPSLatitudeRef as String] = "S" as AnyObject

    }else{
        gps[kCGImagePropertyGPSLatitudeRef as String] = "N" as AnyObject
    }

    gps[kCGImagePropertyGPSLatitude as String] = latitude as AnyObject


    var longitude = location.coordinate.longitude

    if(longitude < 0){
        longitude = -longitude
        gps[kCGImagePropertyGPSLongitudeRef as String] = "W" as AnyObject
    }else{
        gps[kCGImagePropertyGPSLongitudeRef as String] = "E" as AnyObject
    }

    gps[kCGImagePropertyGPSLongitude as String] = longitude as AnyObject

    gps[kCGImagePropertyGPSAltitude as String] = location.altitude as AnyObject

    return gps
}

【讨论】：

你可以多解释一下你的答案

【解决方案6】：

将 GPS 数据写入元数据的类。

class GeoTagImage {

  /// Writes GPS data into the meta data.
  /// - Parameters:
  ///   - data: Coordinate meta data will be written to the copy of this data.
  ///   - coordinate: Cooordinates to write to meta data.
  static func mark(_ data: Data, with coordinate: Coordinate) -> Data {
    var source: CGImageSource? = nil
    source = CGImageSourceCreateWithData((data as CFData?)!, nil)
    // Get all the metadata in the image
    let metadata = CGImageSourceCopyPropertiesAtIndex(source!, 0, nil) as? [AnyHashable: Any]
    // Make the metadata dictionary mutable so we can add properties to it
    var metadataAsMutable = metadata
    var EXIFDictionary = (metadataAsMutable?[(kCGImagePropertyExifDictionary as String)]) as? [AnyHashable: Any]
    var GPSDictionary = (metadataAsMutable?[(kCGImagePropertyGPSDictionary as String)]) as? [AnyHashable: Any]

    if !(EXIFDictionary != nil) {
      // If the image does not have an EXIF dictionary (not all images do), then create one.
      EXIFDictionary = [:]
    }
    if !(GPSDictionary != nil) {
      GPSDictionary = [:]
    }

    // add coordinates in the GPS Dictionary
    GPSDictionary![(kCGImagePropertyGPSLatitude as String)] = coordinate.latitude
    GPSDictionary![(kCGImagePropertyGPSLongitude as String)] = coordinate.longitude
    EXIFDictionary![(kCGImagePropertyExifUserComment as String)] = "Raw Image"

    // Add our modified EXIF data back into the image’s metadata
    metadataAsMutable!.updateValue(GPSDictionary!, forKey: kCGImagePropertyGPSDictionary)
    metadataAsMutable!.updateValue(EXIFDictionary!, forKey: kCGImagePropertyExifDictionary)

    // This is the type of image (e.g., public.jpeg)
    let UTI: CFString = CGImageSourceGetType(source!)!

    // This will be the data CGImageDestinationRef will write into
    let dest_data = NSMutableData()
    let destination: CGImageDestination = CGImageDestinationCreateWithData(dest_data as CFMutableData, UTI, 1, nil)!
    // Add the image contained in the image source to the destination, overidding the old metadata with our modified metadata
    CGImageDestinationAddImageFromSource(destination, source!, 0, (metadataAsMutable as CFDictionary?))

    // Tells the destination to write the image data and metadata into our data object.
    // It will return false if something goes wrong
    _ = CGImageDestinationFinalize(destination)

    return (dest_data as Data)
  }

  /// Prints the Meta Data from the Data.
  /// - Parameter data: Meta data will be printed of this object.
  static func logMetaData(from data: Data) {
    if let imageSource = CGImageSourceCreateWithData(data as CFData, nil) {
      let imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, nil)
      if let dict = imageProperties as? [String: Any] {
        print(dict)
      }
    }
  }
}

【讨论】：

【解决方案7】：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    UIImage *picture = [info objectForKey:UIImagePickerControllerOriginalImage];
    NSData *imageData = UIImagePNGRepresentation(picture);
    CGImageSourceRef sourceRef = CGImageSourceCreateWithData((__bridge CFDataRef)imageData, NULL);
    CFStringRef UTI = CGImageSourceGetType(sourceRef);
    NSMutableData *destinationData = [NSMutableData data];
    CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)destinationData, UTI, 1, NULL);
    NSMutableDictionary *metadata = [[[NSMutableDictionary alloc] initWithDictionary:(__bridge NSDictionary *)CGImageSourceCopyPropertiesAtIndex(sourceRef, 0, NULL)] autorelease];
    
    CGFloat latitude = 54.7;
    CGFloat longitude = 25.3;
    CGFloat altitude = 100.5;
    
    NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
    [dictionary setObject:@(latitude) forKey:(NSString *)kCGImagePropertyGPSLatitude];
    [dictionary setObject:@(longitude) forKey:(NSString *)kCGImagePropertyGPSLongitude];
    [dictionary setObject:@(altitude) forKey:(NSString *)kCGImagePropertyGPSAltitude];
    
    [metadata setObject:dictionary forKey:(NSString *)kCGImagePropertyGPSDictionary];
    
    CGImageDestinationAddImageFromSource(destination, sourceRef, 0, (__bridge CFDictionaryRef)metadata);
    
    BOOL success = CGImageDestinationFinalize(destination);
    
    if (success)
    {
        [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
            PHAssetCreationRequest *request = [PHAssetCreationRequest creationRequestForAsset];
            [request addResourceWithType:PHAssetResourceTypePhoto data:imageData options:nil];
        } completionHandler:^(BOOL success, NSError *error)
         {
            if (error)
            {
                NSLog(@"Error : %@",error);
            }
        }];
    }
    
    CFRelease(destination);
    CFRelease(sourceRef);
}

【讨论】：