iOS图片库照片GPS处理

最近想对图片库里的拍照地点进行批量添加。
定位和获取图片库照片比较好解决。
但是添加地理位置信息就麻烦多了。

单反拍的照片传输进手机之后，是没有地理位置信息的。
找了网上的教程，获取照片地址信息，发现根本获取不到：

NSData *imageData = UIImageJPEGRepresentation(获取的照片, 1);
        CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)imageData, NULL);
        NSDictionary *imageInfo = (__bridge NSDictionary*)CGImageSourceCopyPropertiesAtIndex(source, 0, NULL);
        NSMutableDictionary *metaDataDic = [imageInfo mutableCopy];
        NSMutableDictionary *exifDic =[[metaDataDic objectForKey:(NSString*)kCGImagePropertyExifDictionary]mutableCopy];
        NSMutableDictionary *GPSDic =[[metaDataDic objectForKey:(NSString*)kCGImagePropertyGPSDictionary]mutableCopy];

单反拍摄，没有GPS信息的照片返回：

{
ColorModel = RGB;
Depth = 8;
Orientation = 1;
PixelHeight = 1244;
PixelWidth = 828;
ProfileName = "sRGB IEC61966-2.1";
"{Exif}" = {
ColorSpace = 1;
PixelXDimension = 828;
PixelYDimension = 1244;
};
"{JFIF}" = {
DensityUnit = 0;
JFIFVersion = (
1,
0,
1
);
XDensity = 72;
YDensity = 72;
};
"{TIFF}" = {
Orientation = 1;
};
}

iPhone拍摄，有地理位置信息的照片：

{
ColorModel = RGB;
Depth = 8;
Orientation = 1;
PixelHeight = 1102;
PixelWidth = 826;
ProfileName = "Display P3";
"{Exif}" = {
PixelXDimension = 826;
PixelYDimension = 1102;
};
"{JFIF}" = {
DensityUnit = 0;
JFIFVersion = (
1,
0,
1
);
XDensity = 72;
YDensity = 72;
};
"{TIFF}" = {
Orientation = 1;
};
}

两种都没法获取位置信息。
如果将位置信息写成字典

[GPSDic setObject:[NSNumber numberWithFloat:37.795]
forKey:(NSString)kCGImagePropertyGPSLatitude];
[GPSDic setObject:@"N" forKey:(NSString)kCGImagePropertyGPSLatitudeRef];
[GPSDic setObject:[NSNumber numberWithFloat:122.410]
forKey:(NSString)kCGImagePropertyGPSLongitude];
[GPSDic setObject:@"W" forKey:(NSString)kCGImagePropertyGPSLongitudeRef];
NSLog(@"%@",GPSDic);

强行加上，也无济于事。
突然发现该照片的资源PHAsset信息里，有location属性，是可以拿到位置信息的。那么通过对PHAsset的操作是否可以添加GPS信息呢？

1、

//UIimage转换PHAsset
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
            PHAssetChangeRequest * request = [PHAssetChangeRequest creationRequestForAssetFromImage:image];
            if (request.placeholderForCreatedAsset.localIdentifier) {
                NSString *localIndentifier = request.placeholderForCreatedAsset.localIdentifier;
                PHFetchResult *assetResult = [PHAsset fetchAssetsWithLocalIdentifiers:@[localIndentifier] options:nil];
                PHAsset *asset = assetResult.firstObject;
            }
        } completionHandler:^(BOOL success, NSError * _Nullable error) {
            if (success) {
                NSLog(@"添加成功！");
            } else {
                NSLog(@"添加失败！");
            }
        }];

2、从PHAsset中获取更详细的照片信息：

有地理位置信息的照片{
ColorModel = RGB;
DPIHeight = 72;
DPIWidth = 72;
Depth = 8;
Orientation = 6;
PixelHeight = 3024;
PixelWidth = 4032;
PrimaryImage = 1;
ProfileName = "Display P3";
"{Exif}" = {
ApertureValue = "1.69599381283836";
BrightnessValue = "2.559109103158562";
ColorSpace = 65535;
ComponentsConfiguration = (
1,
2,
3,
0
);
DateTimeDigitized = "2020:07:06 15:06:48";
DateTimeOriginal = "2020:07:06 15:06:48";
ExifVersion = (
2,
3,
1
);
ExposureBiasValue = 0;
ExposureMode = 0;
ExposureProgram = 2;
ExposureTime = "0.05882352941176471";
FNumber = "1.8";
Flash = 16;
FlashPixVersion = (
1,
0
);
FocalLenIn35mmFilm = 28;
FocalLength = 4;
ISOSpeedRatings = (
40
);
LensMake = Apple;
LensModel = "iPhone X back dual camera 4mm f/1.8";
LensSpecification = (
4,
6,
"1.8",
"2.4"
);
MeteringMode = 5;
OffsetTime = "+08:00";
OffsetTimeDigitized = "+08:00";
OffsetTimeOriginal = "+08:00";
PixelXDimension = 4032;
PixelYDimension = 3024;
SceneCaptureType = 0;
SceneType = 1;
SensingMethod = 2;
ShutterSpeedValue = "4.059350611812313";
SubjectArea = (
2015,
1511,
2217,
1330
);
SubsecTimeDigitized = 139;
SubsecTimeOriginal = 139;
WhiteBalance = 0;
};
"{GPS}" = {
Altitude = "4.610363961252704";
AltitudeRef = 0;
DestBearing = "60.45497512437811";
DestBearingRef = T;
HPositioningError = "66.42636786961583";
ImgDirection = "60.45497512437811";
ImgDirectionRef = T;
Latitude = "xx.xxxxxxxxxxxx";
LatitudeRef = N;
Longitude = "xx.xxxxxxxxxxxx";
LongitudeRef = E;
Speed = 0;
SpeedRef = K;
};
"{MakerApple}" = {
1 = 11;
12 = (
"53.55469",
"95.67578"
);
13 = 26;
14 = 0;
15 = 2;
16 = 1;
2 = {length = 512, bytes = 0x88008500 83008600 87008d00 90009200 ... c0004f00 7000b400 };
20 = 5;
23 = 0;
25 = 0;
26 = q825s;
3 = {
epoch = 0;
flags = 1;
timescale = 1000000000;
value = 1645823363837291;
};
31 = 0;
32 = "6DEA2F72-2701-47E0-804C-78F183EEC448";
33 = 0;
35 = (
12,
536871070
);
37 = 0;
38 = 0;
39 = 0;
4 = 1;
43 = "A00C17E9-F64B-46D0-B7FF-BE48307967CF";
5 = 174;
6 = 185;
7 = 1;
8 = (
"0.1065291",
"0.01893699",
"-0.9845731"
);
};
"{TIFF}" = {
DateTime = "2020:07:06 15:06:48";
Make = Apple;
Model = "iPhone X";
Orientation = 6;
ResolutionUnit = 2;
Software = "13.5.1";
TileLength = 512;
TileWidth = 512;
XResolution = 72;
YResolution = 72;
};
}

照片信息比从UIImage中取得的详细多了。

3、更新图片和视频属性（名义上是更新，但是也只能更新四个内容：创建日期、拍照地点、是否收藏、是否隐藏。）

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    PHAssetChangeRequest * changeRequest = [PHAssetChangeRequest changeRequestForAsset:asset];
    changeRequest.location = self.location;
} completionHandler:^(BOOL success, NSError * _Nullable error) {
  if (success) {
    NSLog(@"修改成功");
  } else {
    NSLog(@"修改失败");
  }
}];

参考资料：
https://www.jianshu.com/p/40f3c6e02061 PHAsset的增删改查