I am developing an iOS app in which the user enters their mobile number. How do I get their country calling code? For example, if a user is in India, then +91 s         
        
    NSLocale *currentLocale = [NSLocale currentLocale];  // get the current locale.
    NSString *countryCode = [currentLocale objectForKey:NSLocaleCountryCode];
    // get country code, e.g. ES (Spain), FR (France), etc.
    NSLog(@"country code is:%@",countryCode);
    NSString*lower=[countryCode lowercaseString];
    NSString *path = [[NSBundle mainBundle] pathForResource:@"DiallingCodes" ofType:@"plist"];
    NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:path];
    NSMutableDictionary *_dictCountry=[[NSMutableDictionary alloc]init];
    NSMutableArray *_CodeArray=[[NSMutableArray alloc]init];
    [_CodeArray addObject:dict];
    _dictCountry = [_CodeArray objectAtIndex:0];
    NSString*Country_code=[NSString stringWithFormat:@"+%@",[_dictCountry objectForKey:lower]];
    contactTextField.text=Country_code;
You can request to this url.
For get CountryCode or ip, region_name, city, long, lat
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://freegeoip.net/json/"]];
__block NSDictionary *json;
[NSURLConnection sendAsynchronousRequest:request
                                   queue:[NSOperationQueue mainQueue]
                       completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
                           json = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
                           NSLog(@"Countrycode: %@", json[@"country_code"]);
 }];
Swift
   let networkInfo = CTTelephonyNetworkInfo()
    if let carrier = networkInfo.subscriberCellularProvider {
        print("country code is: " + carrier.mobileCountryCode!);
        //will return the actual country code
        print("ISO country code is: " + carrier.isoCountryCode!);
    }
I came up with the following code, based on previous answers:
#if canImport(CoreTelephony)
import CoreTelephony
#endif
static func getRegionCodeFromSim() -> String? {
  #if canImport(CoreTelephony)
  let networkInfos = CTTelephonyNetworkInfo()
  if #available(iOS 12, *) {
    let carrier = networkInfos.serviceSubscriberCellularProviders?
      .map { $0.1 }
      .first { $0.isoCountryCode != nil }
    return carrier?.isoCountryCode
  }
  return networkInfos.subscriberCellularProvider?.isoCountryCode
  #else
  return nil
  #endif
}
static func getRegionCode() -> String? {
  guard let regionCodeFromSim = Self.getRegionCodeFromSim() else {
    return NSLocale.current.regionCode
  }
  return regionCodeFromSim
}
static func getCountryCode() -> String? {
  guard let regionCode = Self.getRegionCode() else { return nil }
  let prefixCodes = ["AF": "93", "AE": "971", "AL": "355", "AN": "599", "AS":"1", "AD": "376", "AO": "244", "AI": "1", "AG":"1", "AR": "54","AM": "374", "AW": "297", "AU":"61", "AT": "43","AZ": "994", "BS": "1", "BH":"973", "BF": "226","BI": "257", "BD": "880", "BB": "1", "BY": "375", "BE":"32","BZ": "501", "BJ": "229", "BM": "1", "BT":"975", "BA": "387", "BW": "267", "BR": "55", "BG": "359", "BO": "591", "BL": "590", "BN": "673", "CC": "61", "CD":"243","CI": "225", "KH":"855", "CM": "237", "CA": "1", "CV": "238", "KY":"345", "CF":"236", "CH": "41", "CL": "56", "CN":"86","CX": "61", "CO": "57", "KM": "269", "CG":"242", "CK": "682", "CR": "506", "CU":"53", "CY":"537","CZ": "420", "DE": "49", "DK": "45", "DJ":"253", "DM": "1", "DO": "1", "DZ": "213", "EC": "593", "EG":"20", "ER": "291", "EE":"372","ES": "34", "ET": "251", "FM": "691", "FK": "500", "FO": "298", "FJ": "679", "FI":"358", "FR": "33", "GB":"44", "GF": "594", "GA":"241", "GS": "500", "GM":"220", "GE":"995","GH":"233", "GI": "350", "GQ": "240", "GR": "30", "GG": "44", "GL": "299", "GD":"1", "GP": "590", "GU": "1", "GT": "502", "GN":"224","GW": "245", "GY": "595", "HT": "509", "HR": "385", "HN":"504", "HU": "36", "HK": "852", "IR": "98", "IM": "44", "IL": "972", "IO":"246", "IS": "354", "IN": "91", "ID":"62", "IQ":"964", "IE": "353","IT":"39", "JM":"1", "JP": "81", "JO": "962", "JE":"44", "KP": "850", "KR": "82","KZ":"77", "KE": "254", "KI": "686", "KW": "965", "KG":"996","KN":"1", "LC": "1", "LV": "371", "LB": "961", "LK":"94", "LS": "266", "LR":"231", "LI": "423", "LT": "370", "LU": "352", "LA": "856", "LY":"218", "MO": "853", "MK": "389", "MG":"261", "MW": "265", "MY": "60","MV": "960", "ML":"223", "MT": "356", "MH": "692", "MQ": "596", "MR":"222", "MU": "230", "MX": "52","MC": "377", "MN": "976", "ME": "382", "MP": "1", "MS": "1", "MA":"212", "MM": "95", "MF": "590", "MD":"373", "MZ": "258", "NA":"264", "NR":"674", "NP":"977", "NL": "31","NC": "687", "NZ":"64", "NI": "505", "NE": "227", "NG": "234", "NU":"683", "NF": "672", "NO": "47","OM": "968", "PK": "92", "PM": "508", "PW": "680", "PF": "689", "PA": "507", "PG":"675", "PY": "595", "PE": "51", "PH": "63", "PL":"48", "PN": "872","PT": "351", "PR": "1","PS": "970", "QA": "974", "RO":"40", "RE":"262", "RS": "381", "RU": "7", "RW": "250", "SM": "378", "SA":"966", "SN": "221", "SC": "248", "SL":"232","SG": "65", "SK": "421", "SI": "386", "SB":"677", "SH": "290", "SD": "249", "SR": "597","SZ": "268", "SE":"46", "SV": "503", "ST": "239","SO": "252", "SJ": "47", "SY":"963", "TW": "886", "TZ": "255", "TL": "670", "TD": "235", "TJ": "992", "TH": "66", "TG":"228", "TK": "690", "TO": "676", "TT": "1", "TN":"216","TR": "90", "TM": "993", "TC": "1", "TV":"688", "UG": "256", "UA": "380", "US": "1", "UY": "598","UZ": "998", "VA":"379", "VE":"58", "VN": "84", "VG": "1", "VI": "1","VC":"1", "VU":"678", "WS": "685", "WF": "681", "YE": "967", "YT": "262","ZA": "27" , "ZM": "260", "ZW":"263"]
  return prefixCodes[regionCode.uppercased()]
}
It tries to fetch the country code from the SIM cards (with multi-sim & non-sim devices support), if available, and fallbacks to the device's locale otherwise.
The prefixCodes could be loaded from a PLIST or JSON to help with readability.
I think you need to use NSLocale for using Country code of the user.
You can follow this link to understand use of NSLocale class reference.
Also study this link for ISOCountryCode property.
Hope this may help you.
Here the Objective C code
#import<CoreTelephony/CTCarrier.h>
#import <CoreTelephony/CTTelephonyNetworkInfo.h>
- (void)viewDidLoad{
CTTelephonyNetworkInfo *network_Info = [CTTelephonyNetworkInfo new];
 CTCarrier *carrier = network_Info.subscriberCellularProvider;
 NSLog(@"country code is: %@", carrier.mobileCountryCode);
 NSLog(@"ISO country code is: %@", carrier.mobileNetworkCode);
 NSLog(@"diling code == %@",[self getCountryCode:carrier.isoCountryCode]);
}
- (NSString *)getCountryCode:(NSString *)countryISOCode{
    NSDictionary * code = @{@"AF": @"93", @"AE": @"971", @"AL": @"355", @"AN": @"599", @"AS":@"1", @"AD": @"376", @"AO": @"244", @"AI": @"1", @"AG":@"1", @"AR": @"54",@"AM": @"374", @"AW": @"297", @"AU":@"61", @"AT": @"43",@"AZ": @"994", @"BS": @"1", @"BH":@"973", @"BF": @"226",@"BI": @"257", @"BD": @"880", @"BB": @"1", @"BY": @"375", @"BE":@"32",@"BZ": @"501", @"BJ": @"229", @"BM": @"1", @"BT":@"975", @"BA": @"387", @"BW": @"267", @"BR": @"55", @"BG": @"359", @"BO": @"591", @"BL": @"590", @"BN": @"673", @"CC": @"61", @"CD":@"243",@"CI": @"225", @"KH":@"855", @"CM": @"237", @"CA": @"1", @"CV": @"238", @"KY":@"345", @"CF":@"236", @"CH": @"41", @"CL": @"56", @"CN":@"86",@"CX": @"61", @"CO": @"57", @"KM": @"269", @"CG":@"242", @"CK": @"682", @"CR": @"506", @"CU":@"53", @"CY":@"537",@"CZ": @"420", @"DE": @"49", @"DK": @"45", @"DJ":@"253", @"DM": @"1", @"DO": @"1", @"DZ": @"213", @"EC": @"593", @"EG":@"20", @"ER": @"291", @"EE":@"372",@"ES": @"34", @"ET": @"251", @"FM": @"691", @"FK": @"500", @"FO": @"298", @"FJ": @"679", @"FI":@"358", @"FR": @"33", @"GB":@"44", @"GF": @"594", @"GA":@"241", @"GS": @"500", @"GM":@"220", @"GE":@"995",@"GH":@"233", @"GI": @"350", @"GQ": @"240", @"GR": @"30", @"GG": @"44", @"GL": @"299", @"GD":@"1", @"GP": @"590", @"GU": @"1", @"GT": @"502", @"GN":@"224",@"GW": @"245", @"GY": @"595", @"HT": @"509", @"HR": @"385", @"HN":@"504", @"HU": @"36", @"HK": @"852", @"IR": @"98", @"IM": @"44", @"IL": @"972", @"IO":@"246", @"IS": @"354", @"IN": @"91", @"ID":@"62", @"IQ":@"964", @"IE": @"353",@"IT":@"39", @"JM":@"1", @"JP": @"81", @"JO": @"962", @"JE":@"44", @"KP": @"850", @"KR": @"82",@"KZ":@"77", @"KE": @"254", @"KI": @"686", @"KW": @"965", @"KG":@"996",@"KN":@"1", @"LC": @"1", @"LV": @"371", @"LB": @"961", @"LK":@"94", @"LS": @"266", @"LR":@"231", @"LI": @"423", @"LT": @"370", @"LU": @"352", @"LA": @"856", @"LY":@"218", @"MO": @"853", @"MK": @"389", @"MG":@"261", @"MW": @"265", @"MY": @"60",@"MV": @"960", @"ML":@"223", @"MT": @"356", @"MH": @"692", @"MQ": @"596", @"MR":@"222", @"MU": @"230", @"MX": @"52",@"MC": @"377", @"MN": @"976", @"ME": @"382", @"MP": @"1", @"MS": @"1", @"MA":@"212", @"MM": @"95", @"MF": @"590", @"MD":@"373", @"MZ": @"258", @"NA":@"264", @"NR":@"674", @"NP":@"977", @"NL": @"31",@"NC": @"687", @"NZ":@"64", @"NI": @"505", @"NE": @"227", @"NG": @"234", @"NU":@"683", @"NF": @"672", @"NO": @"47",@"OM": @"968", @"PK": @"92", @"PM": @"508", @"PW": @"680", @"PF": @"689", @"PA": @"507", @"PG":@"675", @"PY": @"595", @"PE": @"51", @"PH": @"63", @"PL":@"48", @"PN": @"872",@"PT": @"351", @"PR": @"1",@"PS": @"970", @"QA": @"974", @"RO":@"40", @"RE":@"262", @"RS": @"381", @"RU": @"7", @"RW": @"250", @"SM": @"378", @"SA":@"966", @"SN": @"221", @"SC": @"248", @"SL":@"232",@"SG": @"65", @"SK": @"421", @"SI": @"386", @"SB":@"677", @"SH": @"290", @"SD": @"249", @"SR": @"597",@"SZ": @"268", @"SE":@"46", @"SV": @"503", @"ST": @"239",@"SO": @"252", @"SJ": @"47", @"SY":@"963", @"TW": @"886", @"TZ": @"255", @"TL": @"670", @"TD": @"235", @"TJ": @"992", @"TH": @"66", @"TG":@"228", @"TK": @"690", @"TO": @"676", @"TT": @"1", @"TN":@"216",@"TR": @"90", @"TM": @"993", @"TC": @"1", @"TV":@"688", @"UG": @"256", @"UA": @"380", @"US": @"1", @"UY": @"598",@"UZ": @"998", @"VA":@"379", @"VE":@"58", @"VN": @"84", @"VG": @"1", @"VI": @"1",@"VC":@"1", @"VU":@"678", @"WS": @"685", @"WF": @"681", @"YE": @"967", @"YT": @"262",@"ZA": @"27" , @"ZM": @"260", @"ZW":@"263"};
    return [NSString stringWithFormat:@"+%@", [code objectForKey:[countryISOCode uppercaseString]]];
}