preloadKeyboardDemo.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    [self preloadKeyboard];
    
    return YES;
}

- (void)preloadKeyboard
{
    UITextField *lagFreeTextField = [[UITextField alloc] init];
    [self.window addSubview:lagFreeTextField];
    [lagFreeTextField becomeFirstResponder];
    [lagFreeTextField resignFirstResponder];
    [lagFreeTextField removeFromSuperview];
}