Objective-C

PC/SC Wait for Smart Card Status Change (Inserted, Removed from Reader, etc.)

See more SCard Examples

Demonstrates how to synchronously wait for a status change, such as for a smart card to be inserted into a reader, or removed from a reader.

Note: This functionality was introduced in Chilkat v9.5.0.87.

Objective-C

#import <CkoSCard.h>
#import <CkoJsonObject.h>
#import <NSString.h>
#import <CkoStringBuilder.h>
#import <CkoStringTable.h>

BOOL success = NO;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

CkoSCard *scard = [[CkoSCard alloc] init];

//  First establish a context to the PC/SC Resource Manager
success = [scard EstablishContext: @"user"];
if (success == NO) {
    NSLog(@"%@",scard.LastErrorText);
    return;
}

//  First we'll examine the state of all connected readers to see which have smartcards already inserted..
//  Get JSON containing information about the smartcards currently inserted into readers.
//  This also includes information about USB security tokens.
CkoJsonObject *json = [[CkoJsonObject alloc] init];
success = [scard FindSmartcards: json];
if (success == NO) {
    NSLog(@"%@",scard.LastErrorText);
    return;
}

//  When writing this example, I have 3 smart card readers plugged into my system.
//  One of them has a smart card inserted.
//  Here's the JSON returned by FindSmartcards...

//  {
//    "reader": [
//      {
//        "name": "Alcor Micro USB Smart Card Reader 0",
//        "state": "empty"
//      },
//      {
//        "name": "Generic Smart Card Reader Interface 0",
//        "state": "present",
//        "vendorName": "Generic",
//        "serialNumber": "3230303730383138303030303030303030",
//        "systemName": "Generic Smart Card Reader Interface 0",
//        "card": {
//          "atr": "3BFC180000813180459067464A00641606F2727E00E0",
//          "windows": {
//            "miniDriver": "tagliov70px.dll",
//            "cryptoProvider": "Microsoft Base Smart Card Crypto Provider",
//            "keyStorageProvider": "Microsoft Smart Card Key Storage Provider"
//          }
//        }
//      },
//      {
//        "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
//        "state": "empty"
//      }
//    ]
//  }

json.EmitCompact = NO;
NSLog(@"%@",[json Emit]);
NSLog(@"%@",@" ");

//  We can iterate over the JSON to find the readers with a smart card already inserted..
NSString *name = 0;
CkoStringBuilder *sbState = [[CkoStringBuilder alloc] init];

int i = 0;
int count_i = [[json SizeOfArray: @"reader"] intValue];
while (i < count_i) {
    json.I = [NSNumber numberWithInt: i];
    name = [json StringOf: @"reader[i].name"];

    [sbState Clear];
    [json StringOfSb: @"reader[i].state" sb: sbState];

    if ([sbState Contains: @"present" caseSensitive: YES] == YES) {
        NSLog(@"%@%@",name,@" has a smart card inserted.");
    }
    else {
        NSLog(@"%@%@",name,@" does not have a smart card inserted.");
    }

    i = i + 1;
}

NSLog(@"%@",@" ");

//  Now let's begin the code to wait for a change (where a smart card gets inserted or removed)

//  Get the list of all readers.
CkoStringTable *stReaders = [[CkoStringTable alloc] init];
success = [scard ListReaders: stReaders];
if (success == NO) {
    NSLog(@"%@",scard.LastErrorText);
    return;
}

//  Show the reader names..
int numReaders = [stReaders.Count intValue];
i = 0;
while (i < numReaders) {
    NSLog(@"%d%@%@",i,@": ",[stReaders StringAt: [NSNumber numberWithInt: i]]);
    i = i + 1;
}

//  Sample output from the above loop.
//  0: Alcor Micro USB Smart Card Reader 0
//  1: Generic Smart Card Reader Interface 0
//  2: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
//  

//  Synchronously wait 30 seconds for a card to be inserted or removed from any of the above readers.
CkoJsonObject *json2 = [[CkoJsonObject alloc] init];
success = [scard GetStatusChange: [NSNumber numberWithInt: 30000] stReaderNames: stReaders json: json2];
if (success == NO) {
    NSLog(@"%@",scard.LastErrorText);
    return;
}

NSLog(@"%@",@" ");

//  Let's see what happened...
json2.EmitCompact = NO;
NSLog(@"%@",[json2 Emit]);
NSLog(@"%@",@" ");

//  This is what json2 contains.
//  A card was inserted into the reader named "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"
//  The "numChanged" indicates that one reader's status changed.  
//  The "changed":true indicates the reader that changed.   The state is now "present".

//  {
//    "numChanged": 1,
//    "reader": [
//      {
//        "name": "Alcor Micro USB Smart Card Reader 0",
//        "changed": false,
//        "state": "empty"
//      },
//      {
//        "name": "Generic Smart Card Reader Interface 0",
//        "changed": false,
//        "state": "present",
//        "atr": "3BFC180000813180459067464A00641606F2727E00E0"
//      },
//      {
//        "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
//        "changed": true,
//        "state": "present",
//        "atr": "3BDF96FF8131FE455A018048494443313158587300011B09"
//      }
//    ]
//  }

//  Find the reader that changed...
BOOL changed;
NSString *state = 0;
NSString *atr = 0;

int numChanged = [[json2 IntOf: @"numChanged"] intValue];
NSLog(@"%@%d",@"number of readers with a changed state: ",numChanged);

i = 0;
count_i = [[json2 SizeOfArray: @"reader"] intValue];
while (i < count_i) {
    json2.I = [NSNumber numberWithInt: i];
    changed = [json2 BoolOf: @"reader[i].changed"];
    if (changed == YES) {
        name = [json2 StringOf: @"reader[i].name"];
        state = [json2 StringOf: @"reader[i].state"];

        NSLog(@"%@",@"Changed: ");
        NSLog(@"%@%@",@"    reader name: ",name);
        NSLog(@"%@%@",@"    new state: ",state);

        //  If a card is now in this reader, we should have the ATR of the card..
        if ([json2 HasMember: @"reader[i].atr"] == YES) {
            atr = [json2 StringOf: @"reader[i].atr"];
            NSLog(@"%@%@",@"    ATR of card inserted into this reader: ",atr);
        }

    }

    i = i + 1;
}

//  The output from the above loop:

//  number of readers with a changed state: 1
//  Changed: 
//      reader name: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
//      new state: present
//      ATR of card inserted into this reader: 3BDF96FF8131FE455A018048494443313158587300011B09

//  Applications should always release the context when finished.
success = [scard ReleaseContext];
if (success == NO) {
    NSLog(@"%@",scard.LastErrorText);
}