(Objective-C) DNS Query MX Records

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Shows how to perform a DNS query to retrieve MX records.

Note: This example requires Chilkat v9.5.0.96 or later.

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#import <CkoDns.h>
#import <CkoJsonObject.h>
#import <NSString.h>

CkoDns *dns = [[CkoDns alloc] init];

CkoJsonObject *json = [[CkoJsonObject alloc] init];
json.EmitCompact = NO;

BOOL success = [dns Query: @"MX" domain: @"somebody@gmail.com" answer: json];
if (success == NO) {
    NSLog(@"%@",dns.LastErrorText);
    return;
}

NSLog(@"%@",[json Emit]);

// Sample response.
// Parsing code below..

// -------------------------------------------------------------------------------
// Note: Chilkat will return the results sorted by "pref" from lowest to highest.
// -------------------------------------------------------------------------------

// {
//   "answer": {
//     "mx": [
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 5,
//         "domain": "gmail-smtp-in.l.google.com"
//       },
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 10,
//         "domain": "alt1.gmail-smtp-in.l.google.com"
//       },
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 20,
//         "domain": "alt2.gmail-smtp-in.l.google.com"
//       },
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 30,
//         "domain": "alt3.gmail-smtp-in.l.google.com"
//       },
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 40,
//         "domain": "alt4.gmail-smtp-in.l.google.com"
//       }
//     ]
//   }
// }

// Use this online tool to generate parsing code from sample JSON: 
// Generate Parsing Code from JSON

NSString *name = 0;
int ttl;
int pref;
NSString *domain = 0;

int i = 0;
int count_i = [[json SizeOfArray: @"answer.mx"] intValue];
while (i < count_i) {
    json.I = [NSNumber numberWithInt: i];
    name = [json StringOf: @"answer.mx[i].name"];
    ttl = [[json IntOf: @"answer.mx[i].ttl"] intValue];
    pref = [[json IntOf: @"answer.mx[i].pref"] intValue];
    domain = [json StringOf: @"answer.mx[i].domain"];
    i = i + 1;
}