Unity在Android和iOS中如何调用Native API (2)

 接着上回的话题继续说明。

2. 简单的C# -> C++ -> Java/ObjC -> C#的异步回调实现

这里以在Native层计算加法，然后将计算结果通过异步回调的方式返回给C#层。首先需要在Unity里声明回调的接口，如下所示：

using UnityEngine;

public class UnityCallback : MonoBehaviour {
    public void SumNumResult(string result) {

        print("Result from native = " + result);

        int r = System.Int32.Parse(result);
        TestCallbackManager.sumNumCallback.SendResult(r);

        return;
    }
}

另外需要在C++层分别给出相应的接口实现，如下所示：

★ Android

C++层代码：

void SumNum(int v1, int v2){
        __android_log_print(ANDROID_LOG_INFO, "TestUnity", "START ; invoking SumNum(%d, %d)", v1, v2);

        JNIEnv *env = getJNIEnv();
        initJni(env);

        jmethodID mid = env->GetStaticMethodID(jniClass, "SumNum", "(II)V");

        if (env->ExceptionCheck()) {
            env->ExceptionDescribe();
        }

        env->CallStaticVoidMethod(jniClass, mid, v1, v2);

        if (env->ExceptionCheck()) {
            env->ExceptionDescribe();
        }

        __android_log_print(ANDROID_LOG_INFO, "TestUnity", "END ; invoking SumNum():");
        return;
    }

Java层代码：

public class TestUnity {

    private static final String TAG = "TestUnity";
    // Specify Unity Callback Class
    private static final String UNITYCALLBACK = "UnityCallback";
    // Specify Unity Callback Method
    private static final String SUM_NUM_RESULT = "SumNumResult";

    public static TestUnityActivity activity = null;

    public static void OpenWebView(String url) {
        activity.requestForUrl(url);
    }

    // Mobage API
    public static void SumNum(int v1, int v2) {
        int v = v1 + v2;

        Log.d(TAG, "Result = " + v);
        UnityPlayer.UnitySendMessage(UNITYCALLBACK, SUM_NUM_RESULT, "" + v);
        return;
    }
}

★ iOS

#ifdef __cplusplus
extern "C" {
#endif

extern void UnitySendMessage(const char* obj, const char* method, const char* msg);

void SumNum(int v1, int v2) {
    int v = v1 + v2;
    char s[64];
    sprintf(s, "%d", v);
    UnitySendMessage("UnityCallback", "SumNumResult", s);
}

#ifdef __cplusplus
}
#endif

本例运行时的截图如下所示：