How do I remove UIAppearance settings from UILabel?

Question

How do I remove the setting of UIAppearance already set in UILabel?
Or How do I update already set up UIAppearance?

I created a custom defined UILabel method as follows.

Header

- (void)setAppearanceFont:(UIFont *)font UI_APPEARANCE_SELECTOR;

Implementation

- (void)setAppearanceFont:(UIFont *)font
{
    _invokeCount += 1;

    NSLog(@"invokeCount: %ld", _invokeCount);
    self.font = font;
}

If I set up appearance twice, setAppearanceFont method was invoked twice.

// set appearance
[[MyAppearanceLabel appearance] setAppearanceFont:font];
....
....
// set appearance from another timing
[[MyAppearanceLabel appearance] setAppearanceFont:font];

// show label
MyAppearanceLabel label* = [[MyAppearanceLabel alloc] 
                               initWithFrame:CGRectMake(0, 0, 100, 100)];
[self.view addSubview:label]; // <= invoked twice here!!

I want to ensure that the setAppearance method is invoked only once.

Answer 1

In swift 4 i do as follow(just setting nil to it):

UILabel.appearance(whenContainedInInstancesOf: [UITableViewCell.self]).textColor = nil