Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Determines weather or not all the characters in a string are all the same.
/// </summary>
/// <param name="value">The value to check for.</param>
/// <returns>true is all characters are the same, otherwise false.</returns>
public static bool AllTheSame(this string value)
{
#if UNITY3D
    if (!StringExtensionMethods.IsNullOrWhiteSpace(value))
#else
    if (!string.IsNullOrWhiteSpace(value))
#endif
    {
        var clone = new string(value[0], value.Length);
        return clone == value;
    }

    return false;
}

#if UNITY3D
public static bool IsNullOrWhiteSpace(this string value)
{
    if (value == null)
    {
        return true;
    }

    for (var i = 0; i < value.Length; i++)
    {
        if (!char.IsWhiteSpace(value[i]))
        {
            return false;
        }
    }

    return true;
}
#endif
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

namespace System.Collections
{
    /// <summary>
    /// Provides extension methods for the IList interface.
    /// </summary>
    public static class IListExtensionMethods
    {
        /// <summary>Swaps the specified items in a list.</summary>
        /// <param name="list">The list.</param>
        /// <param name="indexA">The index of item A.</param>
        /// <param name="indexB">The index of item B.</param>
        /// <param name="remove">If set to <c>true</c> items will be removed and re-inserted.</param>
        public static void Swap(this IList list, int indexA, int indexB, bool remove)
        {
            if (indexA == indexB)
            {
                return;
            }

            indexA.IsInRange(0, list.Count - 1, true, "indexA is out of range.");
            indexB.IsInRange(0, list.Count - 1, true, "indexB is out of range.");

            if (remove)
            {
                var first = Math.Min(indexA, indexB);
                var second = Math.Max(indexA, indexB);
                
                var tempA = list[first];
                var tempB = list[second];

                list.RemoveAt(second);
                list.RemoveAt(first);
               
                list.Insert(first, tempB);
                list.Insert(second, tempA);
            }
            else
            {
                var temp = list[indexA];
                list[indexA] = list[indexB];
                list[indexB] = temp;
            }
        }

        /// <summary>Swaps the specified items in a list.</summary>
        /// <param name="list">The list.</param>
        /// <param name="indexA">The index of item A.</param>
        /// <param name="indexB">The index of item B.</param>
        /// <remarks>Items are swapped and not removed or inserted.</remarks>
        public static void Swap(this IList list, int indexA, int indexB)
        {
            Swap(list, indexA, indexB, false);
        }

        /// <summary>Swaps the specified items in a list and return true if successful.</summary>
        /// <param name="list">The list.</param>
        /// <param name="indexA">The index of item A.</param>
        /// <param name="indexB">The index of item B.</param>
        /// <remarks>Items are swapped and not removed or inserted.</remarks>
        /// <returns>true if successful.</returns>
        public static bool TrySwap(this IList list, int indexA, int indexB)
        {
            try
            {
                Swap(list, indexA, indexB);
            }
            catch
            {
                return false;
            }

            return true;
        }

        /// <summary>Swaps the specified items in a list and return true if successful.</summary>
        /// <param name="list">The list.</param>
        /// <param name="indexA">The index of item A.</param>
        /// <param name="indexB">The index of item B.</param>
        /// <param name="remove">If set to <c>true</c> items will be removes and re-inserted.</param>
        /// <returns>true if successful.</returns>
        public static bool TrySwap(this IList list, int indexA, int indexB, bool remove)
        {
            try
            {
                Swap(list, indexA, indexB, remove);
            }
            catch
            {
                return false;
            }

            return true;
        }
    }
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Removes a range of entries inside an array.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="index">The start index where entries will be removed from.</param>
/// <param name="length">The number of entries to be removed.</param>
/// <returns>
/// Returns the resized and updated destination array.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">index</exception>
public static T[] RemoveRange<T>(this T[] array, int index, int length)
{
    if (length < 1)
    {
        return array;
    }

    if (index < 0 || index > array.Length - 1)
    {
        throw new ArgumentOutOfRangeException("index");
    }

    if (index + length > array.Length - 1)
    {
        Array.Resize(ref array, index);
        return array;
    }

    var endLength = Math.Max(0, Math.Min(array.Length - index, array.Length - (index + length)));
    var tempArray = new T[endLength];
    Array.Copy(array, index + length, tempArray, 0, endLength);
    Array.Resize(ref array, array.Length - length);
    tempArray.CopyTo(array, array.Length - endLength);
    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Moves the specified entries in the array by a set ammount.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="index">The start index where entries will be moved from.</param>
/// <param name="length">The number of entries to be moved.</param>
/// <param name="shift">The ammount and direction to move the specified entries.</param>
/// <returns>
/// Returns the resized and updated destination array.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">length;'length' argument must be greater then 0.</exception>
/// <remarks><p>To move entries to the left (towards 0) specify a negative shift value and a positive shift value to move entries to the right.</p>
/// <example>
/// <code>
/// var items = new[] { 0, 1, 2, 3, 4 };
/// items = items.Move(3, 2, -1);
/// </code>
/// Result should be { 0, 1, 3, 4, 4 }
/// </example></remarks>
public static T[] Move<T>(this T[] array, int index, int length, int shift)
{
    if (length <= 0)
    {
        throw new ArgumentOutOfRangeException("length", "'length' argument must be greater then 0.");
    }

    if (shift > 0 && index + length + shift > array.Length - 1)
    {
        Array.Resize(ref array, array.Length + (index + length + shift - array.Length));
    }

    if (index + shift < 0)
    {
        length += index + shift;
        index = -(index + shift);
    }

    length = Math.Min(array.Length - index, length);
    if (length > 0)
    {
        Array.Copy(array, index, array, index + shift, length);
    }        

    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Crops an array to a specified length.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="length">The length that the destination array will be set to.</param>
/// <returns>Returns the resized and updated destination array.</returns>
public static T[] Crop<T>(this T[] array, int length)
{
    if (array == null)
    {
        return array;
    }

    Array.Resize(ref array, Math.Max(length, 0));
    return array;
}

/// <summary>
/// Crops an array to a specified length.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="index">The index in the destination array where cropping begins at.</param>
/// <param name="length">The length that the destination array will be set to.</param>
/// <returns>
/// Returns the resized and updated destination array.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">length;'length' argument must be greater then 0.</exception>
public static T[] Crop<T>(this T[] array, int index, int length)
{
    if (array == null)
    {
        return array;
    }

    if (length <= 0)
    {
        throw new ArgumentOutOfRangeException("length", "'length' argument must be greater then 0.");
    }
                 
    if (index < 0 || index > array.Length - 1)
    {
        return array;
    }
                        
    length = Math.Min(length, array.Length - index);
    if (index > 0)
    {
        Array.Copy(array, index, array, 0, length);
    }

    Array.Resize(ref array, length);
    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Adds the specified source array to the end of the destination array.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="sourceArray">The source array that will be added to the end of the destination array.</param>
/// <returns>Returns the resized and updated destination array.</returns>
public static T[] Add<T>(this T[] array, T[] sourceArray)
{
    if (array == null || sourceArray == null || sourceArray.Length == 0)
    {
        return array;
    }

    Array.Resize(ref array, array.Length + sourceArray.Length);
    sourceArray.CopyTo(array, array.Length - sourceArray.Length);
    return array;
}

/// <summary>
/// Adds a new extry to the end of the destination array.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="value">The item that will be added to the end of the destination array.</param>
/// <returns>Returns the resized and updated destination array.</returns>
public static T[] Add<T>(this T[] array, T value)
{
    if (array == null)
    {
        return array;
    }

    Array.Resize(ref array, array.Length + 1);
    array[array.Length - 1] = value;
    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Replaces a sequence of array entries at the specified index.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="index">The index in the destination array where replacement takes place.</param>
/// <param name="sourceArray">The source array that will replace the existing entries.</param>
/// <returns>Returns the resized and updated destination array.</returns>
/// <exception cref="ArgumentOutOfRangeException">
/// If 'index' is out of bounds of the destination array.
/// </exception>
public static T[] Replace<T>(this T[] array, int index, T[] sourceArray)
{
    if (array == null || sourceArray == null || sourceArray.Length == 0)
    {
        return array;
    }

    if (index < 0)
    {
        throw new ArgumentOutOfRangeException("index");
    }

    if (index > array.Length - 1)
    {
        throw new ArgumentOutOfRangeException("index");
    }

    var expandSize = (index + sourceArray.Length) - array.Length;
    if (expandSize > 0)
    {
        Array.Resize(ref array, array.Length + expandSize);
    }

    sourceArray.CopyTo(array, index);
    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Inserts one array into another array at the specified index.
/// </summary>
/// <typeparam name="T">Specifies the generic type of the array.</typeparam>
/// <param name="array">The destination array.</param>
/// <param name="index">The index in the destination array where insertion takes place.</param>
/// <param name="sourceArray">The source array that will be inserted.</param>
/// <returns>Returns the resized and updated destination array.</returns>
/// <exception cref="ArgumentOutOfRangeException">
/// If 'index' is out of bounds of the destination array.
/// </exception>
public static T[] Insert<T>(this T[] array, int index, T[] sourceArray)
{
    if (array == null || sourceArray == null || sourceArray.Length == 0)
    {
        return array;
    }

    if (index < 0)
    {
        throw new ArgumentOutOfRangeException("index");
    }

    if (index > array.Length + 1)
    {
        throw new ArgumentOutOfRangeException("index");
    }

    Array.Resize(ref array, array.Length + sourceArray.Length);
    Array.Copy(array, index, array, index + sourceArray.Length, array.Length - sourceArray.Length - index);
    sourceArray.CopyTo(array, index);
    return array;
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Removes a depth from the three dimensional sequence.
/// </summary>
/// <typeparam name="T">The type of the array.</typeparam>
/// <param name="array">The array whose values are to be removed.</param>
/// <param name="width">The width of the three dimensional sequence.</param>
/// <param name="height">The height of the three dimensional sequence.</param>
/// <param name="depth">The depth of to be removed from the three dimensional sequence.</param>
/// <returns>Returns the updated three dimensional sequence.</returns>
/// <exception cref="ArgumentOutOfRangeException">
/// width or height is less then 1. Or depth is less then 0 or greater then the depth of the three dimensional sequence.
/// </exception>
public static T[] Remove3DDepth<T>(this T[] array, int width, int height, int depth)
{
    if (width < 1)
    {
        throw new ArgumentOutOfRangeException("width");
    }

    if (height < 1)
    {
        throw new ArgumentOutOfRangeException("height");
    }

    var length = width * height;
    if (depth < 0 || depth > (array.Length / length))
    {
        throw new ArgumentOutOfRangeException("depth");
    }

    return array.RemoveRange(depth * length, length);
}

Full repo available at https://bitbucket.org/createdbyx/codefarts.utilities-extension-methods-only

/// <summary>
/// Gets the depth of the three dimensional sequence.
/// </summary>
/// <typeparam name="T">The type of the array.</typeparam>
/// <param name="array">The array whose value is to be retrieves.</param>
/// <param name="width">The width of the three dimensional sequence.</param>
/// <param name="height">The height of the three dimensional sequence.</param>
/// <returns>Returns the depth of the three dimensional sequence.</returns>
/// <exception cref="ArgumentOutOfRangeException">
/// width or height is less then 1.
/// </exception>
public static int Get3DDepth<T>(this T[] array, int width, int height)
{
    if (width < 1)
    {
        throw new ArgumentOutOfRangeException("width");
    }

    if (height < 1)
    {
        throw new ArgumentOutOfRangeException("height");
    }

    return array.Length / (width * height);
}