UIView.backgroundColor is null in MTKView

I'm trying to get the background color of a view. I'm using Objective-C++ rather than Swift for easier interoperation with a C++ code base. The following test code:


#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    NSLog(@"%@", self.view.backgroundColor);
}

@end


Logs the expected results: null if no color is assigned in the storyboard, else the color object.


If the view is an instance of GLKView (which I know is deprecated), the results are still as expected.


However, if the view is an instance of MTKView, the result is null even when a color is assigned in the storyboard.


I haven't been able to find any explanation for why this would be the case. Is there any reason backgroundColor would return null for specific derived classes of UIView? Is there anything special about MTKView that would cause this to happen?