Objective C - how to convert Degree-Minute-Second to Double

问题

My actual problem is - How to obtain a CLLocation Object when the coordinate value on the map is available in Degree-Minute-Second form (as a String), instead of Double.

So, I am Looking for a way to convert Degree-Minute-Second to Double, which i can use to form a CLLocation object.

回答1:

I came up with a bit of a cleaner answer when figuring this out

// split the string to deal with lat and lon separately
NSArray *parts = [dmsString componentsSeparatedByString:@","];
NSString *latStr = parts[0];
NSString *lonStr = parts[1];

// convert each string
double lat = [self degreesStringToDecimal:latStr];
double lon = [self degreesStringToDecimal:lonStr];

// init your location object
CLLocation *loc = [[CLLocation alloc] initWithLatitude:lat longitude:lon];

The magic

- (double)degreesStringToDecimal:(NSString*)string
{
    // split the string
    NSArray *splitDegs = [string componentsSeparatedByString:@"\u00B0"];  // unicode for degree symbol
    NSArray *splitMins = [splitDegs[1] componentsSeparatedByString:@"'"];
    NSArray *splitSecs = [splitMins[1] componentsSeparatedByString:@"\""];

    // get each segment of the dms string
    NSString *degreesString = splitDegs[0];
    NSString *minutesString = splitMins[0];
    NSString *secondsString = splitSecs[0];
    NSString *direction = splitSecs[1];

    // convert degrees
    double degrees = [degreesString doubleValue];

    // convert minutes
    double minutes = [minutesString doubleValue] / 60;  // 60 degrees in a minute

    // convert seconds
    double seconds = [secondsString doubleValue] / 3600; // 60 seconds in a minute, or 3600 in a degree

    // add them all together
    double decimal = degrees + minutes + seconds;

    // determine if this is negative. south and west would be negative values
    if ([direction.uppercaseString isEqualToString:@"W"] || [direction.uppercaseString isEqualToString:@"S"])
    {
        decimal = -decimal;
    }

    return decimal;
}

Note that I've only tested this with coordinates in Wisconsin, which is North and West. I'm using this tool to verify my calculations.

回答2:

Let's say you have a the coordinate value in a String -

Split the String To obtain Degree-Minute-Second values in separate strings.

NSString *longlat= @"+39° 44' 39.28", -104° 50' 5.86" "(find a way to escape the " in the string)

//separate lat and long
NSArray *splitLonglat = [longlat componentsSeparatedByString:@","];

//separate Degree-Minute-Seconds
NSArray *arrayLat = [[splitLonglat objectAtIndex:0] componentsSeparatedByString:@" "];
double latitude,longitude;
if([arrayLat count]==3){
//get the double value for latitude
latitude= [self convertDMSToDD_deg:(NSString *)[arrayLat objectAtIndex:0]//degree
                               min:(NSString *)[arrayLat objectAtIndex:1]//minute
                               sec:(NSString *)[arrayLat objectAtIndex:2]//seconds
          ];
}else{
         //some values could be in decimal form in the String already, instead of Degree-Minute-Second form and we might not need to convert them.
         NSLog(@"latitude in decimal for %@",locationModelObject.name);
         latitude=[[splitLonglat objectAtIndex:0]doubleValue];
}
NSArray *arrayLong= [[splitLonglat objectAtIndex:1] componentsSeparatedByString:@" "];
            if([arrayLong count]==4){
                //get the double value for longitude
                longitude= [self convertDMSToDD_deg:(NSString *)[arrayLong objectAtIndex:1]//degree
                                                min:(NSString *)[arrayLong objectAtIndex:2]//minute
                                                sec:(NSString *)[arrayLong objectAtIndex:3]//seconds
                            ];
            }else{
                //some values could be in decimal form in the String already, instead of Degree-Minute-Second form and we might not need to convert them.
                NSLog(@"longitude in decimal for %@",locationModelObject.name);
                longitude=[[splitLonglat objectAtIndex:1]doubleValue];
            }
            //add latitude longitude to the model object
            locationModelObject.latitude=latitude;
            locationModelObject.longitude=longitude;

The Method which does the conversion

-(double) convertDMSToDD_deg:(NSString*)degrees min:(NSString* )minutes sec:(NSString*)seconds {

int latsign=1;

double degree=[degrees doubleValue];
double minute=[minutes doubleValue];
double second=[seconds doubleValue];
if (degree<0){
    latsign = -1;
}
else{
    latsign=1;
}
double dd = (degree + (latsign* (minute/60.)) + (latsign* (second/3600.) ) ) ;
return dd;
}

来源：https://stackoverflow.com/questions/13523424/objective-c-how-to-convert-degree-minute-second-to-double

标签

objective-c

ios

mapkit