- (void)downloadZip {

    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];

    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

    //这里我们用本地链接替代一下，可以使用任意url链接

    NSURL *URL = [NSURL URLWithString:@"file:///User/name/Desktop/model.scnassets.zip"];

    NSURLRequest *request = [NSURLRequest requestWithURL:URL];

    NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:nil destination:^NSURL *(NSURL *targetPath, NSURLResponse *response) {

        NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];

        return [documentsDirectoryURL URLByAppendingPathComponent:[response suggestedFilename]];

    } completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {

        NSLog(@"File downloaded to: %@", filePath);

        //对文件解压

        NSArray  *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

        NSString *documentsDirectory = [paths objectAtIndex:];

        NSString *inputPath = [documentsDirectory stringByAppendingPathComponent:@"/product-1-optimized.scnassets.zip"];

        NSError *zipError = nil;

        [SSZipArchive unzipFileAtPath:inputPath toDestination:documentsDirectory overwrite:YES password:nil error:&zipError];

        if( zipError ){

            NSLog(@"[GameVC] Something went wrong while unzipping: %@", zipError.debugDescription);

        }else {

            NSLog(@"[GameVC] Archive unzipped successfully");

            [self startScene];

        }

    }];

    [downloadTask resume];

}

// Create a new scene

SCNScene *scene = [SCNScene scene];

// create and add a camera to the scene

SCNNode *cameraNode = [SCNNode node];

cameraNode.camera = [SCNCamera camera];

[scene.rootNode addChildNode:cameraNode];

// place the camera

cameraNode.position = SCNVector3Make(, , );

// create and add a light to the scene

SCNNode *lightNode = [SCNNode node];

lightNode.light = [SCNLight light];

lightNode.light.type = SCNLightTypeOmni;

lightNode.position = SCNVector3Make(, , );

[scene.rootNode addChildNode:lightNode];

// create and add an ambient light to the scene

SCNNode *ambientLightNode = [SCNNode node];

ambientLightNode.light = [SCNLight light];

ambientLightNode.light.type = SCNLightTypeAmbient;

ambientLightNode.light.color = [UIColor darkGrayColor];

[scene.rootNode addChildNode:ambientLightNode];

// Add our cube to the scene

[scene.rootNode addChildNode:theCube];

// retrieve the SCNView

SCNView *scnView = (SCNView *)self.view;

// set the scene to the view

scnView.scene = scene;

// allows the user to manipulate the camera

scnView.allowsCameraControl = YES;

// show statistics such as fps and timing information

scnView.showsStatistics = YES;

// configure the view

scnView.backgroundColor = [UIColor blackColor];