objective-c - Objective C - 如何将度-分-秒转换为双精度

Question

我的实际问题是 - 当地图上的坐标值以度-分-秒形式（作为字符串）而不是 Double 可用时，如何获取 CLLocation 对象。

所以，我正在寻找一种将度-分-秒转换为双精度的方法，我可以用它来形成一个 CLLocation 对象。

Answer 1

在弄清楚这一点时，我想出了一个更清晰的答案

// 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];

魔法

- (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;
}

请注意，我只使用威斯康星州的坐标（即北部和西部）对此进行了测试。我正在使用这个工具来验证我的计算。

Answer 2

假设您在字符串中有一个坐标值 -

拆分字符串以在单独的字符串中获取度-分-秒值。

• NSString *longlat= @"+39° 44' 39.28", -104° 50' 5.86" "（找到一种方法来逃避"字符串中的）

  //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;
  

进行转换的方法

-(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;
}