Using anchors with Auto Layout is a big improvement over creating constraints using the class function in NSLayoutConstraint or Visual Format Language. You also write your own wrappers to make creating multiple constraints easier, e.g one might write a function like v2ray购买服务号怎么使用? – ssr节点:2021-4-30 · 提供免费最新SSR节点分享，SS节点账号分享，ssr节点教程，用于科学上网、学习与交流使用。 v2ray购买服务号怎么使用最下面会说到。现在先来了解下v2ray 是一个模块化的企理工具，支持 VMess，Socks，HTTP，Shadowsocks 等等协议，并且 ... or NSLayoutConstraint.constraint(views:toSquareWithSides:), both returning an array.

Or sometimes, in a more dynamic piece of UI, you might need to swap around arrays of constraints.

I find it useful to define a protocol and a few extensions so that this can be done:

NSLayoutConstraint.activate([
    constraintsArray1,
    constraintsArray2,
    constraint3,
    constraint4,
    constraint5,
])

Alternatives involve appending of arrays which ends up with code that is hard to indent.

So there you go:

protocol LayoutConstraintsWrapper {
    var constraints: [NSLayoutConstraint] { get }
}

extension Array: LayoutConstraintsWrapper where Element: NSLayoutConstraint {
    var constraints: [NSLayoutConstraint] {
        return self
    }
}

extension NSLayoutConstraint: LayoutConstraintsWrapper {
    var constraints: [NSLayoutConstraint] {
        return [self]
    }
}

extension NSLayoutConstraint {
    class func activate(_ constraints: [LayoutConstraintsWrapper]) {
        activate(constraints.flatMap { $0.constraints })
    }
}

Like this post? Follow me on Twitter.