判断手机是否越狱，只需要调用以下方法(包含三种方式，三选一即可)

- (void) isJailBreak {
    // 第一种方法
   if ([[NSFileManager defaultManager] fileExistsAtPath:@"User/Applications/"]) {
      NSLog(@"isJailBreak1: The device is jail broken!");
      NSArray *appList = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:@"User/Applications/" error:nil];
      NSLog(@"isJailBreak1: appList = %@", appList);
    } else {
      NSLog(@"isJailBreak1: The device is NOT jail broken!");
    }
    // 第二种方法
   if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"cydia://"]]) {
      NSLog(@"isJailBreak2: The device is jail broken!");
   } else {
     NSLog(@"isJailBreak2: The device is NOT jail broken!");
   }
   // 第三种方法
   NSArray *jailbreak_tool_paths = @[@"/Applications/Cydia.app",@"/Library/MobileSubstrate/MobileSubstrate.dylib", @"/bin/bash",@"/usr/sbin/sshd",@"/etc/apt"];
   for (int i = 0; i < jailbreak_tool_paths.count; i++) {
       if ([[NSFileManager defaultManager] fileExistsAtPath:jailbreak_tool_paths[i]]){
        NSLog(@"isJailBreak3:The device is jail broken!");
        return;
       }
   }
  NSLog(@"isJailBreak3: The device is NOT jail broken!");

}