How to detect that the app is running on a jailbroken device?

/**
     Detect that the app is running on a jailbroken device or not

     - returns: bool value for jailbroken device or not
     */
    public class func isDeviceJailbroken() -> Bool {
        #if arch(i386) || arch(x86_64)
            return false
        #else
            let fileManager = FileManager.default

            if (fileManager.fileExists(atPath: "/bin/bash") ||
                fileManager.fileExists(atPath: "/usr/sbin/sshd") ||
                fileManager.fileExists(atPath: "/etc/apt") ||
                fileManager.fileExists(atPath: "/private/var/lib/apt/") ||
                fileManager.fileExists(atPath: "/Applications/Cydia.app") ||
                fileManager.fileExists(atPath: "/Library/MobileSubstrate/MobileSubstrate.dylib")) {
                return true
            } else {
                return false
            }
        #endif
    }

Check for these paths

+ (BOOL)isJailBroken {
#ifdef TARGET_IPHONE_SIMULATOR
    return NO;
#endif

    NSArray *paths = @[@"/bin/bash",
                       @"/usr/sbin/sshd",
                       @"/etc/apt",
                       @"/private/var/lib/apt/",
                       @"/Applications/Cydia.app",
                       ];

    for (NSString *path in paths) {
        if ([self fileExistsAtPath:path]) {
            return YES;
        }
    }

    return NO;
}


+ (BOOL)fileExistsAtPath:(NSString *)path {
    FILE *pFile;
    pFile = fopen([path cStringUsingEncoding:[NSString defaultCStringEncoding]], "r");
    if (pFile == NULL) {
        return NO;
    }
    else
        fclose(pFile);
    return YES;
}

Additionally, you can take a look https://github.com/OneSignal/OneSignal-iOS-SDK/blob/master/iOS_SDK/OneSignalSDK/Source/OneSignalJailbreakDetection.m

Try to find a file which cydia or jailbroken device create. Or try to write in a file outside the app's blackbox. If you succeed to do that, the device is compromised/jailbroken :)

- (BOOL)jailbroken
{
    NSFileManager * fileManager = [NSFileManager defaultManager];
    return [fileManager fileExistsAtPath:@"/private/var/lib/apt/"];
}

You can detect through code that if the app is running on a jail broken device or not. Through that way you can pop up an alert and close the app. You can do whatever you want to do. Here is a tutorial for it:

http://thwart-ipa-cracks.blogspot.com/2008/11/detection.html

and here is a Stack Overflow post:

How do I detect that an iOS app is running on a jailbroken phone?

Also, if you want a complete solution, you can see in tapjoy sdk code. They are detecting jailbroken iPhone. Here is tapjoy URL https://www.tapjoy.com/