nstring: NSString support on macOS

Author: LunaTheFoxgirl

dub.sdl

@@ -11,8 +11,8 @@ buildOptions "debugInfoC" platform="windows"
 // Enable Objective-C integration on apple platforms.
 configuration "appleos" {
     platforms "osx" "ios" "watchos" "tvos" "visionos"
-
     targetType "library"
+
     dependency "objective-d" version="~>1.0" optional=true default=false
 }
 

source/numem/string.d

@@ -157,15 +157,25 @@ public:
         }
     }
 
-    /**
-        Creates a string from an Objective-C NSString.
-
-        This will release 1 reference from the NSString.
-    */
     version(Have_objective_d)
-    this(NSString str) {
-        this.set_(str.toString());
-        str.release();
+    static if (is(T == char)) {
+
+        /**
+            Creates a string from an Objective-C NSString.
+
+            This will release 1 reference from the NSString.
+        */
+        this(NSString str) {
+            this.set_(str.toString());
+            str.release();
+        }
+
+        /**
+            To Objective-C NSString
+        */
+        NSString toNSString() {
+            return NSString.create(ptr);
+        }
     }
 
     /**
@@ -312,14 +322,6 @@ public:
     */
     alias toString = toDString;
 
-    /**
-        To Objective-C NSString
-    */
-    version(Have_objective_d)
-    NSString toNSString() {
-        return NSString.create(ptr);
-    }
-
     /**
         Set content of string
     */