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 car

Answer 1

Complementing the Anneq Anwar answer, here the swift version:

import CoreTelephony
func isSimAvailable()  -> Bool {
    var isSimCardAvailable = true
    var info = CTTelephonyNetworkInfo()
    var carrier = info.subscriberCellularProvider
    if carrier != nil && carrier.mobileNetworkCode == nil || carrier.mobileNetworkCode.isEqual("") {
        isSimCardAvailable = false
    }
    return isSimCardAvailable
}

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fix: The carrier can be nil in some devices