Created
September 29, 2020 18:08
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VFL example
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| import UIKit | |
| final class SomeView: LayoutView | |
| { | |
| let view1 = UIView() | |
| let view2 = UIView() | |
| let view3 = UIView() | |
| override func layout() { | |
| super.layout() | |
| autoLayout.applyVisualFormatLanguage([ | |
| "|-(30)-[view1]-(30)-[view2]-(30)-[view3]" | |
| ]) | |
| } | |
| } | |
| class LayoutView: UIView | |
| { | |
| override init(frame: CGRect) { | |
| super.init(frame: frame) | |
| layout() | |
| } | |
| @available(*, unavailable) | |
| required init?(coder aDecoder: NSCoder) { | |
| super.init(coder: aDecoder) | |
| layout() | |
| } | |
| func layout() { | |
| autoLayout.enumerateSubViews().values.forEach { addSubview($0) } | |
| } | |
| } | |
| public extension UIView { | |
| var autoLayout: AutoLayout { | |
| AutoLayout(self) | |
| } | |
| } | |
| public struct AutoLayout { | |
| public let base: UIView | |
| public init(_ base: UIView) { | |
| self.base = base | |
| } | |
| public func applyVisualFormatLanguage(_ constraints: [String], | |
| options: NSLayoutConstraint.FormatOptions = [], | |
| metrics: [String: Any]? = nil) { | |
| base.translatesAutoresizingMaskIntoConstraints = false | |
| var views = enumerateSubViews() | |
| views["baseView"] = base | |
| views.values.forEach { $0.translatesAutoresizingMaskIntoConstraints = false } | |
| constraints.forEach { | |
| base.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: $0, options: options, metrics: metrics, views: views)) | |
| } | |
| } | |
| /// Returns every non nil instance UIView variable in the given view, indexed by its variable name. | |
| public func enumerateSubViews() -> [String: UIView] { | |
| var views = [String: UIView]() | |
| let mirror = Mirror(reflecting: base) | |
| let addToViewsClosure: ((Mirror.Child) -> Void) = { child in | |
| child.label.flatMap { label in | |
| // lazy var has $__lazy_storage_$_ (swift 5.1+) and .storage (swift 5-) in `label` property. | |
| #if swift(>=5.1) | |
| let key = label.replacingOccurrences(of: "$__lazy_storage_$_", with: "") | |
| #else | |
| let key = label.replacingOccurrences(of: ".storage", with: "") | |
| #endif | |
| views[key] = child.value as? UIView | |
| } | |
| } | |
| mirror.children.forEach(addToViewsClosure) | |
| mirror.superclassMirror?.children.forEach(addToViewsClosure) | |
| return views | |
| } | |
| } |
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