+ (void)setFontName:(NSString*)fontName onObject:(id)object {
       if ([object respondsToSelector:@selector(setFont:)]) {
           UIFont* font = [UIFont fontWithName:fontName size:((UIFont *)[object font]).pointSize];
           [object setFont:font];
       }
}

public static func setFontRewriting(fontName: String, object: AnyObject) {
    if object.responds(to:#selector(setter: object.font)) {
        let currentFont: UIFont = object.font
        let fontToSet = UIFont(name: fontName, size: currentFont.pointSize)
        object.font = UIFont(name: fontName, size: currentFont.pointSize) //doesn't work, getting various syntax errors
    }
}