iPhone - Detecting SIM card availability

Question

I am using the answer in this topic. iPhone - how to determine carrier of the device (AT&T, Verizon, etc?) which is the same as getting operator details in iphone. Although it works fine when using a sim card, the returned carrier name if there is no SIM card is the old carrier name. It doesn't detect that the SIM is removed.

I know this contradicts with Apple documentation that if there is no carrier, CTCarrier object shall be nil. But in my app I logged the carrier info and it gives me the latest carrier name although no sim is installed.

Answer 1

Swift version:

func hasCellularCoverage() -> Bool {

    let networkInfo = CTTelephonyNetworkInfo()

    guard let info = networkInfo.subscriberCellularProvider else {return false}

    if let carrier = info.isoCountryCode {
        print("No sim present Or No cellular coverage or phone is on airplane mode. Carrier = \(carrier)");
        return true
    }

    return false

}

or

func hasCellularCoverage() -> Bool {

    let networkInfo = CTTelephonyNetworkInfo()

    guard let info = networkInfo.subscriberCellularProvider else {return false}

    return info.isoCountryCode != nil ? true : false

}

Answer 2

The CTCarrier object has 5 properties:

allowsVOIP
carrierName
isoCountryCode
mobileCountryCode
mobileNetworkCode

I have made some tests regarding CTCarrier and I have come to the conclusion that for iOS 7 only carrierName and allowsVOIP are retained when SIM is removed. isoCountryCode, mobileCountryCode and mobileNetworkCode are reset for iOS 7. That's how you can detect if a SIM is present or not.

For iOS 6 all the values are retained.

I performed the tests using an iPhone 4S and iPhone 5 both running iOS 7.

Answer 3

@import CoreTelephony;

-(BOOL)hasCellularCoverage
{
    CTTelephonyNetworkInfo *networkInfo = [CTTelephonyNetworkInfo new];
    CTCarrier *carrier = [networkInfo subscriberCellularProvider];


    if (!carrier.isoCountryCode) {
        NSLog(@"No sim present Or No cellular coverage or phone is on airplane mode.");
        return NO;
    }
    return YES;
}

Answer 4

According to the documentation for [CTCarrier carrierName]:

If you configure a device for a carrier and then remove the SIM card, this property retains the name of the carrier.

As far as I know, you cannot detect if the SIM card is installed. You can only determine if a WWAN connection is available using Reachability.