iOS Get Signal Strength in Swift (Core Telephony)

Question

I'm new to iOS, and am learning to code with Swift. My app needs to measure the signal strength. I've found this code working on Objective-C/C, and need some help to implement on Swift. Here is what I got. Hope someone can help me finish it.

OBJECTIVE C

    int getSignalStrength()
    {
       void *libHandle = dlopen("/System/Library/Frameworks/CoreTelephony.framework/CoreTelephony", RTLD_LAZY);
       int (*CTGetSignalStrength)();
       CTGetSignalStrength = dlsym(libHandle, "CTGetSignalStrength");
       if( CTGetSignalStrength == NULL) NSLog(@"Could not find CTGetSignalStrength");
       int result = CTGetSignalStrength();
       dlclose(libHandle);
       return result;
    }

SWIFT

    func getSignalStrength()->Int{
       var result : Int! = 0
       let libHandle = dlopen ("/System/Library/Frameworks/CoreTelephony.framework/CoreTelephony", RTD_LAZY)
       ** help **
       var CTGetSignalStrength = dlsym(libHandle, "CTGetSignalStrength")
       if (CTGetSignalStrength != nil){
           result = CTGetSignalStrength()
       }
       dlclose(libHandle)
       return result
    }

Answer 1

Swift 3 Solution

import CoreTelephony
import Darwin

    static func getSignalStrength()->Int{
        var result : Int = 0
        //int CTGetSignalStrength();
        let libHandle = dlopen ("/System/Library/Frameworks/CoreTelephony.framework/CoreTelephony", RTLD_NOW)
        let CTGetSignalStrength2 = dlsym(libHandle, "CTGetSignalStrength")

        typealias CFunction = @convention(c) () -> Int

        if (CTGetSignalStrength2 != nil) {
            let fun = unsafeBitCast(CTGetSignalStrength2!, to: CFunction.self)
            let result = fun()
            return result;
            print("!!!!result \(result)")
        } 
     return -1
 }

Answer 2

Don't use dlopen to load CoreTelephony. Use import CoreTelephony at the top of your Swift file. Then just use CTGetSignalStrength as if it were any other function.