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Unity应用程序中从目标C到C的回调释放内存时出现内存问题

unity3d objective-c c#

batuman · 技术社区 · 7 年前

在Unity应用程序中,我需要将char*从目标C传递到C#。现在的问题是,当使用free()释放char*时,应用程序会崩溃。

在目标C端有一个回调函数

Unitybridge.mm

static UnityMultipleDevicesCallback MultipleDevicesLastCallBack = NULL;
void MultipleDevicesConnectCallback(UnityMultipleDevicesCallback callbackMethod)
{
    NSLog(@"callback is assigned");
    MultipleDevicesLastCallBack = callbackMethod;//a simple assignment using the connect method

}

void MultipleDevicesCallMethod(NSMutableArray *devices)
{
    NSLog(@"devices: %@", devices);
    if(MultipleDevicesLastCallBack != NULL){
        @autoreleasepool {
           devs_ = (char*)malloc([devices count]+1 * sizeof(char));

           for (NSString *s in devices) {

               if(strlen(devs_) > 0){
                   const char *d = "/";
                   strcat(devs_,d);
                   strcat(devs_, [s UTF8String] );
               }
               else{
                   strcpy(devs_, [s UTF8String]);
               }

           }           
        }

        MultipleDevicesLastCallBack(devs_);

    }
}
void Freedevs_()
{

    if(devs_!=nullptr){
        free(devs_);
        NSLog(@"devs_ is free now");
    }

}

在C侧,

     //
    [DllImport ("__Internal")]
    private static extern void Freedevs_();
    //Callback
    public delegate void UnityMultipleDevicesCallbackDelegate(string devices);
    [DllImport ("__Internal")]
    public static extern void MultipleDevicesConnectCallback(UnityMultipleDevicesCallbackDelegate callbackMethod);
    [MonoPInvokeCallback(typeof(UnityMultipleDevicesCallbackDelegate))]
    private static void MultipleDevicesCallback(string devices)
    {

        BLEdevices = (String)devices.Clone();
        Debug.Log ("Multiple devices callback now " + BLEdevices);
        //Freedevs_ ();
    }

我尝试了两种选择。一个是 @autoreleasepool 第二个是不使用 @自动释放池 ,我打电话 void Freedevs_() .

使用 @自动释放池 ,有时不确定它是否有效,有时应用程序会崩溃。如果我调用Freedevs\uz(),应用程序肯定会崩溃。

解决这个问题的办法是什么?

1 回复 | 直到 7 年前

batuman 7 年前

我很幸运找到了这篇文章 here .

根据文章,我需要使用 [MarshalAs(UnmanagedType.LPStr)] 在我的C侧并更新。请注意 I don't use malloc anymore and that is sort of not reliable thing in such usage .

    Objectiv C
    void MultipleDevicesCallMethod(NSMutableArray *devices)
    {


      if(MultipleDevicesLastCallBack != NULL){
           NSString *d = @"";
           int cnt = 0;
           for (NSString *s in devices) {
               d = [d stringByAppendingString:s];
               if(cnt < [devices count]-1 &&  [devices count] > 1 ){
                   d = [d stringByAppendingString:@"/"];
                   cnt++;
               }

           }
           const char* devs_ =  [d cStringUsingEncoding:NSUTF8StringEncoding];
           MultipleDevicesLastCallBack(devs_);


      }       

    }

     C#
     public delegate void UnityMultipleDevicesCallbackDelegate(string devices);
    [DllImport ("__Internal", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
    public static extern void MultipleDevicesConnectCallback(UnityMultipleDevicesCallbackDelegate callbackMethod);
    [MonoPInvokeCallback(typeof(UnityMultipleDevicesCallbackDelegate))]
    private static void MultipleDevicesCallback([MarshalAs(UnmanagedType.LPStr)]string devices)
    {

        BLEdevices = (String)devices.Clone();
        Debug.Log ("Multiple devices callback now " + BLEdevices);
        Freedevs_ ();
    }