Possible way to detect sim card detection in ios?

Question

I have a iphone app that has the capability to send messages. I want to alert user when sim card is not available in iphone. So i tried below three function to check sim card availabilty

Class messageClass = (NSClassFromString(@"MFMessageComposeViewController"));
if([messageClass canSendText]){
    // Sim available
    NSLog(@"Sim available");
}
else{
    //Sim not available
    NSLog(@"Sim not available");
}

if([MFMessageComposeViewController canSendText]){
    // Sim available
    NSLog(@"Sim available");
}
else{
    //Sim not available
    NSLog(@"Sim not available");
}

if([[UIDevice currentDevice].model isEqualToString:@"iPhone"])
{
    if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"tel:123456"]])
    {
        NSLog(@"Sim available");
    }
    else
    {
        NSLog(@"Sim not available");
    }
}

I have checked my iphone without sim, it always return @"Sim available". But when i open default "Messages" app and try to send sms it says alert "No SIM Card Installed"... How this message app can detect sim card availabilty?

Answer 1

By the below code you can get the sim card details like carriername,mobilecountrycode,isocountrycode,mobilenetworkcode.In the ios 6 all are retained.So if your sim card is removed also it will retain the old details.So there this idea wont be useful but in ios 7 only carriername is retained and remaining are changed so the below code can be used

CTTelephonyNetworkInfo* info = [[CTTelephonyNetworkInfo alloc] init];
CTCarrier* carrier = info.subscriberCellularProvider;
NSString *mobileCountryCode = carrier.mobileCountryCode;
NSString *carrierName = carrier.carrierName;
NSString *isoCountryCode = carrier.isoCountryCode;
NSString *mobileNetworkCode = carrier.mobileNetworkCode

// Try this to track CTCarrier changes 
info.subscriberCellularProviderDidUpdateNotifier = ^(CTCarrier* inCTCarrier) {
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"User did change SIM");
        });
};