Change the background of a UILabel in ViewController when I slide left or right a Slider in a Settings Bundle

Question

I need to change 1 label background using a Sliders located in a Settings Bundler. When I slide to right my UILabel background need to get a shade of red and when I change to left my UILabel need to get a shade of black.

Here I have 3 screenshots with my Bundle, ViewController and my code.

 // slider 1 - When I slide to left: Shade of black    Slide to right: shade of red
    if userDefaults.integer(forKey: "sliderOne_preference") >= 0 &&  userDefaults.integer(forKey: "sliderOne_preference") <= 49 {
        labelOne.backgroundColor = .black
    }
    else if userDefaults.integer(forKey: "sliderOne_preference") > 49 &&  userDefaults.integer(forKey: "sliderOne_preference") <= 100 {
        labelOne.backgroundColor = .red
    }

    // slider 2 - When I slide to left: Shade of black    Slide to right: shade of blue
    if userDefaults.integer(forKey: "sliderTwo_preference") >= 0 &&  userDefaults.integer(forKey: "sliderTwo_preference") <= 49 {
        labelTwo.backgroundColor = .black
    }
    else if userDefaults.integer(forKey: "sliderTwo_preference") > 49 &&  userDefaults.integer(forKey: "sliderTwo_preference") <= 100 {
        labelTwo.backgroundColor = .blue
    }

Thanks !