Issue Linking Box2D application on OS X - c++

Question

I have an SDL game I have been working on as my first somewhat real project. I decided to introduce Box2D physics as I was not happy with the collision detection. So I installed it to /usr/local/lib/Box2D and in the folder is Box2D.h and supporting folders. I am using MacVim to code on OSX 10.9.2 to develop, and clang++ compiler from the command line.
In my game code I am just trying to create a simple world to test things out:
#include <Box2D/Box2D.h>
.......
world = new b2World(b2Vec2(0.0,9.81));
My make command finds the library, but errors out trying to build.
$ make clean && make
rm -rf obj bin
clang++ -Wall -c -std=c++11 -I/usr/local/lib src/Ball.cpp -o obj/Ball.o
clang++ -Wall -c -std=c++11 -I/usr/local/lib src/Game.cpp -o obj/Game.o
clang++ -Wall -c -std=c++11 -I/usr/local/lib src/Paddle.cpp -o obj/Paddle.o
clang++ -Wall -c -std=c++11 -I/usr/local/lib src/TextureManager.cpp -o obj/TextureManager.o
clang++ -Wall -c -std=c++11 -I/usr/local/lib src/main.cpp -o obj/main.o
clang++ -framework SDL2 -framework SDL2_image -F /Library/Frameworks -L/usr/local/lib/Box2D obj/Ball.o obj/Game.o obj/Paddle.o obj/TextureManager.o obj/main.o -o bin/game
Undefined symbols for architecture x86_64:
"b2World::b2World(b2Vec2 const&)", referenced from:
Game::init() in Game.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [game] Error 1
And here is my Makefile. Box2D is in /usr/local/lib/Box2D/Box2D.h. I am pretty sure my issue is somewhere in the Makefile.
CXX = clang++
CXXFLAGS = -Wall -c -std=c++11 -I/usr/local/lib
SDL = -framework SDL2 -framework SDL2_image
LDFLAGS = $(SDL) -F /Library/Frameworks -L/usr/local/lib/Box2D
SRC_DIR = src
SOURCES = $(wildcard $(SRC_DIR)/*.cpp)
OBJ_DIR = obj
OBJECTS = $(subst $(SRC_DIR)/, $(OBJ_DIR)/, $(patsubst %.cpp, %.o, $(SOURCES)))
#$(warning $(OBJECTS))
BIN_DIR = bin
EXE = game
# run these no matter what
.PHONY: all clean run
all: $(EXE)
$(EXE): $(OBJECTS)
#mkdir -p $(BIN_DIR)
$(CXX) $(LDFLAGS) $(OBJECTS) -o $(BIN_DIR)/$(EXE)
$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
#mkdir -p $(OBJ_DIR)
$(CXX) $(CXXFLAGS) $< -o $#
clean:
rm -rf obj bin
run:
./$(BIN_DIR)/$(EXE)

Answer 1

It does not appear that you ever actually link the Box2D library anywhere? You use -L to specify directories to search while linking, but I don't see a -l option to actually link the Box2D library (whatever it's called).
Your output line seems to bear this out:
clang++ -framework SDL2 -framework SDL2_image -F /Library/Frameworks -L/usr/local/lib/Box2D obj/Ball.o obj/Game.o obj/Paddle.o obj/TextureManager.o obj/main.o -o bin/game
You need to get -lbox2d (or whatever the correct name for the Box2D library is) in there.