将AVMetadataItem的GPS字符串转换为CLLocation

Question

AVAsset (或AVURLAsset)在数组中包含AVMetadataItems，其中一个可能是公用密钥AVMetadataCommonKeyLocation。

该项的值是以如下格式显示的字符串：

+39.9410-075.2040+007.371/

如何将该字符串转换为CLLocation？

Answer 1

好的，我发现字符串是ISO 6709格式，然后找到了一些相关的Apple示例代码。

NSString* locationDescription = [item stringValue];

NSString *latitude  = [locationDescription substringToIndex:8];
NSString *longitude = [locationDescription substringWithRange:NSMakeRange(8, 9)];

CLLocation* location = [[CLLocation alloc] initWithLatitude:latitude.doubleValue 
                                                  longitude:longitude.doubleValue];

以下是苹果的示例代码：AVLocationPlayer

此外，这里还有转换回的代码：

+ (NSString*)iso6709StringFromCLLocation:(CLLocation*)location
{
    //Comes in like
    //+39.9410-075.2040+007.371/
    //Goes out like
    //+39.9410-075.2040/
    if (location) {
        return [NSString stringWithFormat:@"%+08.4f%+09.4f/",
            location.coordinate.latitude,
            location.coordinate.longitude];
    } else {
        return nil;
    }
}

Answer 2

我处理相同的问题，并且在Swift中有相同的代码，而不使用substring：

这里是locationString

+39.9410-075.2040+007.371/

let indexLat = locationString.index(locationString.startIndex, offsetBy: 8)
let indexLong = locationString.index(indexLat, offsetBy: 9)

let lat = String(locationString[locationString.startIndex..<indexLat])
let long = String(locationString[indexLat..<indexLong])

if let lattitude = Double(lat), let longitude = Double(long) {
      let location = CLLocation(latitude: lattitude, longitude: longitude)
}