iOS 拍照中加入GPS和具体地理位置

时间：2022-11-09 08:27:02

最近有一个需求，要求用手机拍个照片，并切需要拍摄时间，拍摄gps，拍摄具体街道信息。

首先要感谢PhotoGPSdemo的作者，你可以到这里下载demo http://www.cocoachina.com/bbs/read.php?tid=130501。

以前，总认为jpg就是包含了像素信息的2进制文件，其实，jpg中还可以包含许多起它的信息，只不过我们平常用查看jpg属性时，系统没有给我们把信息全部显示出来而已！

在iOS中，提供了一组函数来操作jpg的这些额外的信息，你需要#import <ImageIO/ImageIO.h>才能使用他们。

首先，需要注意的是，UIImage对象中是没有这些信息的，它仅仅包含图像本身，jpg才包含这些信息，请不要弄混。

先看看怎么从jpg图片中取得各种额外信息，代码如下

- (IBAction)test

{

    NSString * home = NSHomeDirectory();

    NSData *data = [NSData dataWithContentsOfFile:[NSString stringWithFormat:@"%@/Documents/xx.jpg",home]];

    CGImageSourceRef imgSource = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);

    CFDictionaryRef metaDataDicRef = CGImageSourceCopyPropertiesAtIndex(imgSource,,nil);

    NSLog(@"cfdictionary %@",(__bridge NSDictionary *)metaDataDicRef);

    NSDictionary *dic = (__bridge NSDictionary *)metaDataDicRef;

    NSDictionary *exifDic = [dic objectForKey:(NSString *)kCGImagePropertyExifDictionary];

    NSString *location = [exifDic objectForKey:(NSString *)kCGImagePropertyExifCameraOwnerName];

    NSLog(@"location is %@",location);

    NSString *DateTimeOriginal = [exifDic objectForKey:(NSString *)kCGImagePropertyExifDateTimeOriginal];

    NSLog(@"time is %@",DateTimeOriginal);

    CFRelease(metaDataDicRef);

    CFRelease(imgSource);

}

首先，需要用到CGImageSourceRef类，不能用UIImage类型(需要验证。。。)，这种CGImageSourceRef类型可以通过函数取出jpg的额外数据，这些数据叫做metaData，翻译过来就是元数据。得到的metaData是以字典形式返回的，其中的key是固定的，具体声明见下方

CFStringRef kCGImagePropertyTIFFDictionary;

CFStringRef kCGImagePropertyGIFDictionary;

CFStringRef kCGImagePropertyJFIFDictionary;

CFStringRef kCGImagePropertyExifDictionary;

CFStringRef kCGImagePropertyPNGDictionary;

CFStringRef kCGImagePropertyIPTCDictionary;

CFStringRef kCGImagePropertyGPSDictionary;

CFStringRef kCGImagePropertyRawDictionary;

CFStringRef kCGImagePropertyCIFFDictionary;

CFStringRef kCGImageProperty8BIMDictionary;

CFStringRef kCGImagePropertyDNGDictionary;

CFStringRef kCGImagePropertyExifAuxDictionary;

这些key中，有许多key对应的对象还是一个字典，比如kCGImagePropertyExifDictionary所对应的对象包含一下key值

const CFStringRef kCGImagePropertyExifExposureTime;

const CFStringRef kCGImagePropertyExifFNumber;

const CFStringRef kCGImagePropertyExifExposureProgram;

const CFStringRef kCGImagePropertyExifSpectralSensitivity;

const CFStringRef kCGImagePropertyExifISOSpeedRatings;

const CFStringRef kCGImagePropertyExifOECF;

const CFStringRef kCGImagePropertyExifVersion;

const CFStringRef kCGImagePropertyExifDateTimeOriginal;

const CFStringRef kCGImagePropertyExifDateTimeDigitized;

const CFStringRef kCGImagePropertyExifComponentsConfiguration;

const CFStringRef kCGImagePropertyExifCompressedBitsPerPixel;

const CFStringRef kCGImagePropertyExifShutterSpeedValue;

const CFStringRef kCGImagePropertyExifApertureValue;

const CFStringRef kCGImagePropertyExifBrightnessValue;

const CFStringRef kCGImagePropertyExifExposureBiasValue;

const CFStringRef kCGImagePropertyExifMaxApertureValue;

const CFStringRef kCGImagePropertyExifSubjectDistance;

const CFStringRef kCGImagePropertyExifMeteringMode;

const CFStringRef kCGImagePropertyExifLightSource;

const CFStringRef kCGImagePropertyExifFlash;

const CFStringRef kCGImagePropertyExifFocalLength;

const CFStringRef kCGImagePropertyExifSubjectArea;

const CFStringRef kCGImagePropertyExifMakerNote;

const CFStringRef kCGImagePropertyExifUserComment;

const CFStringRef kCGImagePropertyExifSubsecTime;

const CFStringRef kCGImagePropertyExifSubsecTimeOrginal;

const CFStringRef kCGImagePropertyExifSubsecTimeDigitized;

const CFStringRef kCGImagePropertyExifFlashPixVersion;

const CFStringRef kCGImagePropertyExifColorSpace;

const CFStringRef kCGImagePropertyExifPixelXDimension;

const CFStringRef kCGImagePropertyExifPixelYDimension;

const CFStringRef kCGImagePropertyExifRelatedSoundFile;

const CFStringRef kCGImagePropertyExifFlashEnergy;

const CFStringRef kCGImagePropertyExifSpatialFrequencyResponse;

const CFStringRef kCGImagePropertyExifFocalPlaneXResolution;

const CFStringRef kCGImagePropertyExifFocalPlaneYResolution;

const CFStringRef kCGImagePropertyExifFocalPlaneResolutionUnit;

const CFStringRef kCGImagePropertyExifSubjectLocation;

const CFStringRef kCGImagePropertyExifExposureIndex;

const CFStringRef kCGImagePropertyExifSensingMethod;

const CFStringRef kCGImagePropertyExifFileSource;

const CFStringRef kCGImagePropertyExifSceneType;

const CFStringRef kCGImagePropertyExifCFAPattern;

const CFStringRef kCGImagePropertyExifCustomRendered;

const CFStringRef kCGImagePropertyExifExposureMode;

const CFStringRef kCGImagePropertyExifWhiteBalance;

const CFStringRef kCGImagePropertyExifDigitalZoomRatio;

const CFStringRef kCGImagePropertyExifFocalLenIn35mmFilm;

const CFStringRef kCGImagePropertyExifSceneCaptureType;

const CFStringRef kCGImagePropertyExifGainControl;

const CFStringRef kCGImagePropertyExifContrast;

const CFStringRef kCGImagePropertyExifSaturation;

const CFStringRef kCGImagePropertyExifSharpness;

const CFStringRef kCGImagePropertyExifDeviceSettingDescription;

const CFStringRef kCGImagePropertyExifSubjectDistRange;

const CFStringRef kCGImagePropertyExifImageUniqueID;

const CFStringRef kCGImagePropertyExifGamma;

const CFStringRef kCGImagePropertyExifCameraOwnerName;

const CFStringRef kCGImagePropertyExifBodySerialNumber;

const CFStringRef kCGImagePropertyExifLensSpecification;

const CFStringRef kCGImagePropertyExifLensMake;

const CFStringRef kCGImagePropertyExifLensModel;

const CFStringRef kCGImagePropertyExifLensSerialNumber;

这里的每一个key都有具体的含义，代表了jpg的一些信息。这些key和key的值时有严格的格式限定的，你用了自己定义的key或者不符合规则的值，是不能正确地写入jpg文件的（待会要提到如何写入metaData信息）。

如何用UIImagePickerController拍摄照片后加入信息呢？用这个控件拍照后，默认生成的metaData信息较少，只有拍摄时间等几个信息，没有gps信息，更没有街道信息，我们需要手动加入。



#pragma mark - UIImagePickerControllerDelegate






- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info




{




_mediaInfo =[NSMutableDictionarydictionaryWithDictionary:info];






if (!_locationManager) {




_locationManager = [[CLLocationManager alloc]init];




[_locationManagersetDelegate:self];




[_locationManagersetDistanceFilter:kCLDistanceFilterNone];




[_locationManagersetDesiredAccuracy:kCLLocationAccuracyBest];




}




[_locationManagerstartUpdatingLocation];






[picker dismissViewControllerAnimated:YEScompletion:^




{






}];




}






#pragma mark CLLocationManagerDelegate




- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation{




[manager stopUpdatingLocation];






UIImage *originalImage= (UIImage *) [_mediaInfoobjectForKey:UIImagePickerControllerOriginalImage];




NSData *imageNSData = UIImageJPEGRepresentation(originalImage,1);






CGImageSourceRef imgSource = CGImageSourceCreateWithData((__bridge CFDataRef)imageNSData, NULL);




//this is the type of image (e.g., public.jpeg)




CFStringRef UTI = CGImageSourceGetType(imgSource);






//this will be the data CGImageDestinationRef will write into




NSMutableData *newImageData = [NSMutableDatadata];




CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge  CFMutableDataRef)newImageData, UTI, 1, NULL);






if(!destination)




{




NSLog(@"***Could not create image destination ***");




return;




}






//get original metadata




NSDictionary *dict = [_mediaInfoobjectForKey:UIImagePickerControllerMediaMetadata];




NSMutableDictionary *metadata = [NSMutableDictionarydictionaryWithDictionary:dict];






//set gps info into metadata,we need a dictionary




NSDictionary * gpsDict=[newLocation GPSDictionary];




if (metadata && gpsDict) {




[metadata setValue:gpsDict forKey:(NSString*)kCGImagePropertyGPSDictionary];




}






//get location detail by CLGeocoder, this needs wifi




CLGeocoder *geocoder = [[CLGeocoder alloc] init];




[geocoder reverseGeocodeLocation:newLocation completionHandler:^(NSArray *placemarks, NSError *error){




if(error != nil)




{




NSLog(@"CLGeocoder error :%@ ",error);




}




else//if we can get place info ,we set it into meteData dic with kCGImagePropertyExifCameraOwnerName key




{




if(placemarks.count > 0)




{




CLPlacemark *placemark = [placemarks objectAtIndex:0];




NSMutableDictionary *eifDic = (NSMutableDictionary *)[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary];




[eifDic setObject:placemark.nameforKey:(NSString *)kCGImagePropertyExifCameraOwnerName];




}




}






//add the image contained in the image source to the destination, overidding the old metadata with our modified metadata




CGImageDestinationAddImageFromSource(destination, imgSource, 0, (__bridge  CFDictionaryRef) metadata);






BOOL success = NO;




success = CGImageDestinationFinalize(destination);






if(!success) {




NSLog(@"***Could not create data from image destination ***");




return ;




}






CFRelease(imgSource);




CFRelease(destination);






[self sendData:newImageData];




[self writeTest:newImageData];






}];








}




 


@implementation CLLocation (GPSDictionary)


-(NSDictionary*)GPSDictionary{


NSDateFormatter *formatter  = [[NSDateFormatteralloc] init];


[formatter setDateFormat:@"hh:mm:ss.SS"];


CLLocation *location=self;


NSDictionary *gpsDict   = [NSDictionarydictionaryWithObjectsAndKeys:


[NSNumbernumberWithFloat:fabs(location.coordinate.latitude)], kCGImagePropertyGPSLatitude,


((location.coordinate.latitude >= 0) ? @"N" : @"S"), kCGImagePropertyGPSLatitudeRef,


[NSNumbernumberWithFloat:fabs(location.coordinate.longitude)], kCGImagePropertyGPSLongitude,


((location.coordinate.longitude >= 0) ? @"E" : @"W"), kCGImagePropertyGPSLongitudeRef,


[formatter stringFromDate:[location timestamp]], kCGImagePropertyGPSTimeStamp,


nil];


NSLog(@"gpsDict i %@",gpsDict);


return gpsDict;


}


@end


 




上面代码需要手动改改，它的最终目的就是用 CGImageDestinationAddImageFromSource(destination, imgSource, 0, (__bridge CFDictionaryRef) metadata);函数用新的metaData信息生成新的jpg数据。


其中gps数据用了系统自定义的key值写入，街道信息没有找到合适的key，就冒用了kCGImagePropertyExifCameraOwnerName这个key。
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