macOS Drawn string changes in color but not in size

    NSString *sNumber = [[NSString alloc] initWithFormat:@"%d", num]; // convert number into string
    
    NSMutableDictionary *attrib = [[NSMutableDictionary alloc] init]; // create a dictionary
    [attrib setObject:[NSColor colorWithDeviceRed:0 green:0.5 blue:0 alpha:1] forKey:NSForegroundColorAttributeName]; // change the color to dark green (works)
    [attrib setObject:@40 forKey:NSFontSizeAttribute]; // tries to change the size of the font to 40 (doesn't work)
        
    NSMutableAttributedString *masNumber = [[NSMutableAttributedString alloc] initWithString:sNumber attributes:attrib]; // create an attributed string with given string and attributes.
    
    NSSize omvang = [masNumber size]; // calculate the size
    NSLog(@"getal: %d, breedte: %f, hoogte: %f", num, omvang.width, omvang.height); // log the width, the height and the value (converted into string
    NSPoint startTekstPunt = NSMakePoint(tekstPunt.x - omvang.width / 2, tekstPunt.y - omvang.height / 2); // calculate were to draw
    [masNumber drawAtPoint:startTekstPunt]; // draw the string