Make a child view stretch the full width and height of its parent with some margins // use system-standard margins Parent.addConstraints(nstraints(withVisualFormat: "V:||", metrics: nil, views: viewsDictionary)) Parent.addConstraints(nstraints(withVisualFormat: "H:||", metrics: nil, views: viewsDictionary)) Make a child view stretch the full width and height of its parent let viewsDictionary = Creating constraints using Visual Format LanguageĪlthough it’s not something you’ll see often, Visual Format Language (VFL) can help you get started making constraints because it has a relatively simple API for basic layouts. Note: Be careful when using absolute sizes, because it can cause problems with labels if their text overflows. make the child exactly 200 points highĬ(equalToConstant: 200).isActive = true Make a child view have a precise size // make the child exactly 200 points wideĬ(equalToConstant: 200).isActive = true make sure the child is the width Apple recommends for comfortable readingĬ(equalTo: ),Ĭ(equalTo: ) give the child the system-recommended margins on the leading and trailing edgesĬ(equalTo: ),Ĭ(equalTo: ) Make a child have a natural width in its parentĪuto Layout gives us two useful layout guides: one that comes with the suggested system margin, and one that ensures a readable width for text. There’s also lessThanOrEqualTo for the opposite effect. We’ve been using equality constraints above, but here’s an example using greater than or equal to: NSLayoutConstraint.activate([Ĭ(greaterThanOrEqualTo:, constant: 20),Ĭ(greaterThanOrEqualTo:, constant: 20) Make a child stay a certain distance away from the edges of its parent For example, using 1:2 will make the child view half the width of its parent. Tip: If you’re using storyboards to make your Auto Layout constraints, you can also use ratios as your multiplier for things like width and height. give the child the same width as its parent, minus a little padding on the edgesĬ(equalTo: parent.widthAnchor, constant: -40).isActive = true give the child half the width as its parentĬ(equalTo: parent.widthAnchor, multiplier: 0.5).isActive = true give the child the same height as its parentĬ(equalTo: parent.heightAnchor).isActive = true Make a child view match the size of its parent // give the child the same width as its parentĬ(equalTo: parent.widthAnchor).isActive = true This will make a child view run to the edges of the safe area layout guides of its parent, which means it won’t go near rounded corners or the home indicator: NSLayoutConstraint.activate([Ĭ(equalTo: ),Ĭ(equalTo: ),Ĭ(equalTo: ),Ĭ(equalTo: ) Pin a child view to the safe area guides of its parent Tip: When activating or deactivating lots of constraints at once, it’s more efficient to pass them as an array to activate() and deactivate() respectively. You should mostly use leading and trailing anchors rather than left and right anchors, because leading and trailing automatically flip when your app is running in a right-to-left locale. This will make the child view run to the very edges of its parent: NSLayoutConstraint.activate([Ĭ(equalTo: parentView.leadingAnchor),Ĭ(equalTo: ailingAnchor),Ĭ(equalTo: parentView.topAnchor),Ĭ(equalTo: parentView.bottomAnchor) In the code below I’ve used childView and parentView as names of example views, where the child is placed inside the parent. Sponsor Hacking with Swift and reach the world's largest Swift community! AnchorsĪuto Layout anchors are by far the easiest way to make constraints, and they also happen to have a really natural form too. SPONSORED Join a FREE crash course for mid/senior iOS devs who want to achieve an expert level of technical and practical skills – it’s the fast track to being a complete senior developer! Hurry up because it'll be available only until October 1st.
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