Assign the terraindata of terrain collider

im creating my terrain at runtime with a midpoint displacement algorithm; im also creating the terrain component at run time

so i dont have any terrain data to drag into the colider ( as it doesnt exist until run time)

 HeightMap h = new HeightMap (513, roughness);
 
         h.AddMidPointDisplacement ();
 
         TerrainData t = new TerrainData ();
         t.size = new Vector3 (150, 1000, 150);
         t.alphamapResolution = 512;
         t.heightmapResolution = 513;
         t.SetDetailResolution (512, 8);
         t.baseMapResolution = 512;
         t.SetHeights (0, 0, h.Heights);
 
         GameObject myTerrain = Terrain.CreateTerrainGameObject (t);
 
         myTerrain.GetComponent<TerrainCollider> ().terrainData = t;

everyt$$anonymous$$gn else works, my terrain generates perfectly, my splatmaps work perfectly, the only t$$anonymous$$ng i cant seem to get to work is assigning the terrain data to the collider;

when i created the terrain object, it adds the collider to the object automatically, but doesnt assign the terrain data to the collider.