iOS jailbreak detection

iOS jailbreak detection

/* return true if phone is jail broken */
+ (BOOL) checkJailbreak
{
#if (TARGET_OS_SIMULATOR)
    return NO;
#endif
    
    /* checking fork */
    pid_t child = fork();
    if (child > 0) {
        return YES;
    }
    
    /* checking for existence of files */
    NSArray *fileNames =
    @[
      @"/Applications/Cydia.app",
      @"/Library/MobileSubstrate/MobileSubstrate.dylib",
      @"/var/cache/apt",
      @"/var/lib/apt",
      @"/var/lib/cydia",
      @"/var/log/syslog",
      @"/var/tmp/cydia.log",
      @"/bin/bash",
      @"/bin/sh",
      @"/usr/sbin/sshd",
      @"/usr/libexec/ssh-keysign",
      @"/etc/ssh/sshd_config",
      @"/etc/apt"
      ];
    
    for (NSString *fileName in fileNames) {
        if ([[NSFileManager defaultManager] fileExistsAtPath:fileName])
        {
            NSLog(@"File exists: %@", fileName);
            return YES;
        }
    }
    
    /* checking for ability to write into /private */
    NSError *error;
    NSString *testWriteText = @"Jailbreak test";
    NSString *testWritePath = @"/private/jailbreaktest.txt";
    
    [testWriteText writeToFile:testWritePath atomically:YES encoding:NSUTF8StringEncoding error:&error];
    
    if (error == nil)
    {
        [[NSFileManager defaultManager] removeItemAtPath:testWritePath error:nil];
        return YES;
    }
    else
    {
        [[NSFileManager defaultManager] removeItemAtPath:testWritePath error:nil];
    }
    
    /* checking for ability to open cydia:// link */
    if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"cydia://package/com.example.package"]])
    {
        return YES;
    }
    
    return NO;
}