UiViewExtensions.cs

using System;
using System.Collections.Generic;
using System.Linq;
using CoreGraphics;
using UIKit;

namespace Kitta.Extensions
{
    public enum KtDimension { Height, Width }
    
    public static class UiViewExtensions
    {
        /// <summary>
        /// Sets the view to a specific size.
        /// </summary>
        /// <param name="view"></param>
        /// <param name="size"></param>
        /// <returns></returns>
        public static NSLayoutConstraint[] AutoSetDimension(this UIView view, CGSize size)
        {
            IList<NSLayoutConstraint> constraints = new List<NSLayoutConstraint>(2);
            constraints.Add(view.AutoSetDimension(KtDimension.Height, size.Height));
            constraints.Add(view.AutoSetDimension(KtDimension.Width, size.Width));
            return constraints.ToArray();
        }

        /// <summary>
        /// Sets the given dimension of the view to a specific size.
        /// </summary>
        /// <param name="view"></param>
        /// <param name="dimension"></param>
        /// <param name="constant"></param>
        /// <returns></returns>
        public static NSLayoutConstraint AutoSetDimension(this UIView view, KtDimension dimension, nfloat constant)
        {
            var constraint = new NSLayoutConstraint();
            
            switch (dimension)
            {
                case KtDimension.Height:
                    constraint = view.HeightAnchor.ConstraintEqualTo(constant);
                    break;
                case KtDimension.Width:
                    constraint = view.WidthAnchor.ConstraintEqualTo(constant);
                    break;
            }
            
            constraint.Active = true;
            return constraint;
        }

        /// <summary>
        /// Matches a dimension of the view to a given dimension of another view.
        /// </summary>
        /// <param name="view"></param>
        /// <param name="dimension"></param>
        /// <param name="peerView"></param>
        /// <returns></returns>
        public static NSLayoutConstraint AutoSetDimension(this UIView view, KtDimension dimension, UIView peerView)
        {
            return view.AutoSetDimension(dimension, peerView, 0);
        }
        
        /// <summary>
        /// Matches a dimension of the view to a given dimension of another view with an offset.
        /// </summary>
        /// <param name="view"></param>
        /// <param name="dimension"></param>
        /// <param name="peerView"></param>
        /// <param name="constant"></param>
        /// <returns></returns>
        public static NSLayoutConstraint AutoSetDimension(this UIView view, KtDimension dimension, UIView peerView,
            nfloat constant)
        {
            var constraint = new NSLayoutConstraint();
            
            switch (dimension)
            {
                case KtDimension.Height:
                    constraint = view.HeightAnchor.ConstraintEqualTo(peerView.HeightAnchor, constant);
                    break;
                case KtDimension.Width:
                    constraint = view.WidthAnchor.ConstraintEqualTo(peerView.WidthAnchor, constant);
                    break;
            }
            
            constraint.Active = true;
            return constraint;
        }
        
        /// <summary>
        /// Return the layoutGuide for the correct iOS Version
        /// Before iOS 11 -> Margin Area Guide
        /// >= iOS 11 -> Safe Area Guide
        /// </summary>
        /// <param name="view"></param>
        /// <returns></returns>
        public static UILayoutGuide LayoutGuide(this UIView view)
        {
            return UIDevice.CurrentDevice.CheckSystemVersion(11, 0)
                ? view.SafeAreaLayoutGuide
                : view.LayoutMarginsGuide;
        }
    }
}