Error passing an UnsafeMutablePointer to a function

Question

i am an ios developer who uses swift. I am using an sdk in order to communicate with an ip camera retrieve data from it, and show it to the user. I ve a project shipped with the sdk, which is written in obj c, and is working without problems. The problem is i am not able to pass the parameter to the expected parameter type from the function. The SDK is very old, i integrated it using static libraries and a bridging header and i was able to connect successfully to the camera. I think the sdk is written in c or c++, and i am basically having problems with the parameter conversion.

Fos.h

typedef struct   
{ 
int                       channel;
long long                 time;
unsigned int              index;
FOSMEDIATYPE              type;     //Is video or audio
FOSDECFMT                 fmt;      //The format of video or audio.
short                     isKey;
short                     multiAudioPage;
int                       frameTag; 
union{ 
    FOSVIDEO_INFO      video;       //Media type is video.
    FOSAUDIO_INFO      audio;       //Media type is audio.
} media;
unsigned long long      pts;        //Pts.
unsigned int              len;      //Size of data.
char                      data[0];  //Just data.
}ATTRIBUTE_PACKED FOSDEC_DATA;    //Save the video or audio data,include video or audio information.

.

Objective C function, currently working

- (IBAction)login:(id)sender {
//[self._imageView add]
NSString* str = [self._textField text];
const char* url = [str UTF8String];
char ip[128];
int port;
char usr[64];
char pwd[64];
int count = sscanf(url, "%[^:]:%d/%[^:]:%s", ip, &port, usr, pwd);
if (count != 4) {
    return;
}

mHandle = FosSdk_Create(ip, "", usr, pwd, port, port, FOSIPC_H264, FOSCNTYPE_IP);
//mHandle = FosSdk_Create(ip, "FASDFDSAFDASFASD", usr, pwd, port, port, FOSIPC_H264, FOSCNTYPE_P2P);
if (mHandle == FOSHANDLE_INVALID) {
    return;
}
[self._Login setEnabled:NO];
[self._Logout setEnabled:YES];

[NSThread detachNewThreadSelector:@selector(RunInThread:) toTarget:self withObject:^(void *param){

    int usrPrivilege = 0;
    FOSCMD_RESULT ret = FosSdk_Login(mHandle, &usrPrivilege, 500);
    if (FOSCMDRET_OK != ret) {
        return;
    }

    ret = FosSdk_OpenVideo(mHandle, FOSSTREAM_SUB, 500);
    if (FOSCMDRET_OK != ret) {
        return;
    }
    //char* framebuf = (char*)malloc(512*1024);
    FOSDEC_DATA* data = NULL;

    int outlen = 0;
    while (mHandle) {
// FosSdk_RetainHandle(mHandle, &usrPrivilege);
        if ( FOSCMDRET_OK == FosSdk_GetVideoData(mHandle, (char**)&data, &outlen, FOSDECTYPE_RGB24) && outlen>0)
        {

            if (data->type == FOSMEDIATYPE_VIDEO) {
                //int a=0;
                //a++;
                [self imageFromAVPicture:data->data width:data->media.video.picWidth height:data->media.video.picHeight];
            }
            else{
            }
        }
        usleep(20*1000);
    }
 }];
}

.

The method signature in fos.h

    FOSSDK FOSCMD_RESULT FOSAPI FosSdk_GetVideoData(FOSHANDLE handle, char **data, int *outLen, FOSDECFMT videoFmt);

.

When calling it from objective-c

FosSdk_GetVideoData(<#unsigned int handle#>, <#char **data#>, <#int *outLen#>, <#FOSDECFMT videoFmt#>)
}];

.

When calling it from swift

FosSdk_GetVideoData(handle: UInt32,
                   data: UnsafeMutablePointer?>!,
                   outLen: UnsafeMutablePointer!,
                   videoFmt: FOSDECFMT)

.

The error is data parameter, exactly:

Cannot convert value of type 'UnsafeMutablePointer' to expected argument type 'UnsafeMutablePointer?'

.

I ve tried changing the declaration of data to this, but it gives me this error

let data = UnsafeMutablePointer(&fosdecData)
Ambiguous use of 'init'

.

This pointer stuff is a bit complicated but i was able to pair my device with the camera, using methods which used unsafeMutablePointers too. However, i cannot figure out how to pass this empy data object to the function.

The SDK is outdated and bad documented, which does not help. Anyway, i need to make it working. Hope to get some help, thanks coders! .

EDIT, THANKS TO OOPer . Here is the updated version in swift, which actually produces an unexpected error. The result returned from the function is now 0, so it s correct. However, trying to access original FosdedData struct, i have a Command failed due to signal: Segmentation fault: 11. How could i solve this? Sorry for long question, i wanted to be accurate.

var mhandle : UInt32 = FOS_HANDLE_INIT.rawValue

override func viewDidLoad() {
    super.viewDidLoad()

    //These functions basically do camera pairing, and write result on mhandle, which is equal to 0 , if functions work, otherwise 1
    initializeFOS()
    startEzLinkFOS()
    sdkCreateFOS()
    loginFOS()
    openVideoFOS()        

    var data: UnsafeMutablePointer? = nil
    var outlen : Int32 = 0
    while self.mhandle > 0 {
        let resultOOPer = withUnsafeMutablePointer(to: &data) { pointerToFosdecData in
            pointerToFosdecData.withMemoryRebound(to: UnsafeMutablePointer?.self, capacity: 1, { (pointerToInt8Pointer) in

                FosSdk_GetVideoData(self.mhandle, pointerToInt8Pointer, &outlen, FOSDECTYPE_RGB24)
            })
        }

        if resultOOPer == FOSCMDRET_OK && outlen > 0{
            if let unwrData = data {

                //if unwrData.pointee.type == FOSMEDIATYPE_VIDEO{
                //Produced Output when i try access pointee, which is actually the fosdecData struct i need:
                //Command failed due to signal: Segmentation fault: 11
                //}
            }
        }
        usleep(20*1000)
    }


}

Error passing an UnsafeMutablePointer to a function

1 Answers