Restrict Unity UI to an iPhone X or other Mobile Device's Safe Area

PinToSafeArea.cs

using UnityEngine;

/// <summary>
/// Resizes a UI element with a RectTransform to respect the safe areas of the current device.
/// This is particularly useful on an iPhone X, where we have to avoid the notch and the screen
/// corners.
/// 
/// The easiest way to use it is to create a root Canvas object, attach this to a "SafeAreaContainer"
/// child of that canvas, and then to lay out other UI elements within the SafeAreaContainer, which
/// will adjust size appropriately for the current device.
/// </summary>
public class PinToSafeArea : MonoBehaviour {

    private Rect lastSafeArea;
    private RectTransform parentRectTransform;

    private void Start() {
        parentRectTransform = this.GetComponentInParent<RectTransform>();
    }

    private void Update() {
        if ( lastSafeArea != Screen.safeArea ) {
            ApplySafeArea();
        }
    }

    private void ApplySafeArea() {
        Rect safeAreaRect = Screen.safeArea;

        float scaleRatio = parentRectTransform.rect.width / Screen.width;

        var left = safeAreaRect.xMin * scaleRatio;
        var right = -( Screen.width - safeAreaRect.xMax ) * scaleRatio;
        var top = -safeAreaRect.yMin * scaleRatio;
        var bottom = ( Screen.height - safeAreaRect.yMax ) * scaleRatio;

        RectTransform rectTransform = GetComponent<RectTransform>();
        rectTransform.offsetMin = new Vector2( left, bottom );
        rectTransform.offsetMax = new Vector2( right, top );

        lastSafeArea = Screen.safeArea;
    }
}