Make the replaceGroup argument optional

[strangeliu]

while there is a optional constraintGroup that i have to replace it when it's not nil, i have do like this

var replaceGroup: ConstraintGroup?
if let replaceGroup = replaceGroup {
    constrain(view, replace: replaceGroup) { view in
        // new constrains
    }
} else {
    constrain(view) { view in
        // new constrains
    }
}

or

constrain(view, replace: replaceGroup ?? ConstraintGroup()) { view in
    // new constrains
}

both are not convenient, so make the replaceGroup argument optional for convenient

[orta]

👍 Awesome - thanks!