Add iOS platform (refactor Mac into shared Apple platform impl)

Source/Engine/Platform/Apple/AppleThread.h

@@ -0,0 +1,75 @@
+// Copyright (c) 2012-2023 Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#if PLATFORM_MAC || PLATFORM_IOS
+
+#include "../Unix/UnixThread.h"
+#include <signal.h>
+
+/// <summary>
+/// Thread object for Apple platform.
+/// </summary>
+class FLAXENGINE_API AppleThread : public UnixThread
+{
+public:
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AppleThread"/> class.
+    /// </summary>
+    /// <param name="runnable">The runnable.</param>
+    /// <param name="name">The thread name.</param>
+    /// <param name="priority">The thread priority.</param>
+    AppleThread(IRunnable* runnable, const String& name, ThreadPriority priority)
+        : UnixThread(runnable, name, priority)
+    {
+    }
+    
+public:
+
+    /// <summary>
+    /// Factory method to create a thread with the specified stack size and thread priority
+    /// </summary>
+    /// <param name="runnable">The runnable object to execute</param>
+    /// <param name="name">Name of the thread</param>
+    /// <param name="priority">Tells the thread whether it needs to adjust its priority or not. Defaults to normal priority</param>
+    /// <param name="stackSize">The size of the stack to create. 0 means use the current thread's stack size</param>
+    /// <returns>Pointer to the new thread or null if cannot create it</returns>
+    static AppleThread* Create(IRunnable* runnable, const String& name, ThreadPriority priority = ThreadPriority::Normal, uint32 stackSize = 0)
+    {
+        return (AppleThread*)Setup(New<AppleThread>(runnable, name, priority), stackSize);
+    }
+
+protected:
+
+    // [UnixThread]
+    int32 GetThreadPriority(ThreadPriority priority) override
+    {
+        switch (priority)
+        {
+        case ThreadPriority::Highest:
+            return 45;
+        case ThreadPriority::AboveNormal:
+            return 37;
+        case ThreadPriority::Normal:
+            return 31;
+        case ThreadPriority::BelowNormal:
+            return 25;
+        case ThreadPriority::Lowest:
+            return 20;
+        }
+        return 31;
+    }
+    int32 Start(pthread_attr_t& attr) override
+    {
+        return pthread_create(&_thread, &attr, ThreadProc, this);
+    }
+    void KillInternal(bool waitForJoin) override
+    {
+        if (waitForJoin)
+            pthread_join(_thread, nullptr);
+        pthread_kill(_thread, SIGKILL);
+    }
+};
+
+#endif