Needed to pass the renderer in.

Xcode-iPhoneOS/Demos/src/touch.c

@@ -97,7 +97,7 @@ main(int argc, char *argv[])
 
     /* fill canvass initially with all black */
     SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
-    SDL_RenderClear();
+    SDL_RenderClear(renderer);
     SDL_RenderPresent(renderer);
 
     done = 0;