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

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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.

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

// 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
BOOL 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);
}