How to set the width of a button in snapkit to be the smallest it can be and not exceed a max width

I have a button and I want it to be as small as possible so it just encloses the text but if the button is too big keep it constrained by the size of the containing view inset by 2 standard units.

This is my code now:

    backButton.snp.makeConstraints { make in
        make.centerX.equalToSuperview()
        make.top.equalTo(containerView.snp.bottom).offset(2.su)
        make.trailing.leading.lessThanOrEqualToSuperview().inset(2.su)
    }

The problem with it is that it sizes immediately to take up the space in trailing and leading constraints. Is there a way for it to take less space?

You need to set leading to be greaterThanOrEqualToSuperview or trailing to be lessThanOrEqualToSuperview. Since you set centerX to center, you don't need both.

And when you set them as lessThanOrEqualToSuperview, trailing works fine, but leading interferes with it.

backButton.snp.makeConstraints { make in
    make.centerX.equalToSuperview()
    make.top.equalTo(containerView.snp.bottom).offset(2.su)
    make.trailing.lessThanOrEqualToSuperview().inset(2.su)
}