misc: Use selector fields

src/Ryujinx.Graphics.Metal.SharpMetalExtensions/NSHelper.cs

@@ -1,19 +1,23 @@
 using SharpMetal.Foundation;
 using SharpMetal.ObjectiveCCore;
 using System.Runtime.Versioning;
+// ReSharper disable InconsistentNaming
 
 namespace Ryujinx.Graphics.Metal.SharpMetalExtensions
 {
     [SupportedOSPlatform("macOS")]
     public static class NSHelper
     {
+        private static readonly Selector sel_getCStringMaxLengthEncoding = "getCString:maxLength:encoding:";
+        private static readonly Selector sel_stringWithUTF8String = "stringWithUTF8String:";
+        
         public static unsafe string ToDotNetString(this NSString source)
         {
             char[] sourceBuffer = new char[source.Length];
             fixed (char* pSourceBuffer = sourceBuffer)
             {
                 ObjectiveC.bool_objc_msgSend(source,
-                    "getCString:maxLength:encoding:",
+                    sel_getCStringMaxLengthEncoding,
                     pSourceBuffer,
                     source.MaximumLengthOfBytes(NSStringEncoding.UTF16) + 1,
                     (ulong)NSStringEncoding.UTF16);
@@ -23,6 +27,6 @@ namespace Ryujinx.Graphics.Metal.SharpMetalExtensions
         }
         
         public static NSString ToNSString(this string source) 
-            => new(ObjectiveC.IntPtr_objc_msgSend(new ObjectiveCClass("NSString"), "stringWithUTF8String:", source));
+            => new(ObjectiveC.IntPtr_objc_msgSend(new ObjectiveCClass(nameof(NSString)), sel_stringWithUTF8String, source));
     }
 }