How to detect if your iPhone is jailbroken [duplicate]

Question

If I want my app to behave differently on a jailbroken iPhone, how would I go about determining this?

Answer 1

It depends what you mean by jailbreak. In the simple case, you should be able to see if Cydia is installed and go by that - something like

NSString *filePath = @"/Applications/Cydia.app";
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath])
{
   // do something useful
}

For hacked kernels, it's a little (lot) more involved.

Answer 2

This is a code that combine some answers I found for this need, and will give you much higher success rate :

BOOL isJailbroken()
{
#if !(TARGET_IPHONE_SIMULATOR)

   if ([[NSFileManager defaultManager] fileExistsAtPath:@"/Applications/Cydia.app"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/Library/MobileSubstrate/MobileSubstrate.dylib"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/bin/bash"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/usr/sbin/sshd"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/etc/apt"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/private/var/lib/apt/"] ||
       [[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"cydia://package/com.example.package"]])  {
         return YES;
   }

   FILE *f = NULL ;
   if ((f = fopen("/bin/bash", "r")) ||
      (f = fopen("/Applications/Cydia.app", "r")) ||
      (f = fopen("/Library/MobileSubstrate/MobileSubstrate.dylib", "r")) ||
      (f = fopen("/usr/sbin/sshd", "r")) ||
      (f = fopen("/etc/apt", "r")))  {
         fclose(f);
         return YES;
   }
   fclose(f);

   NSError *error;
   NSString *stringToBeWritten = @"This is a test.";
   [stringToBeWritten writeToFile:@"/private/jailbreak.txt" atomically:YES encoding:NSUTF8StringEncoding error:&error];
   [[NSFileManager defaultManager] removeItemAtPath:@"/private/jailbreak.txt" error:nil];
   if(error == nil)
   {
      return YES;
   }

#endif

   return NO;
}