create a library with helper methods for autolayout

Author: mikhailChelbaev

.gitignore

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+.DS_Store
+/.build
+/Packages
+xcuserdata/
+DerivedData/
+.swiftpm/configuration/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc

Package.swift

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+// swift-tools-version:5.9
+
+import PackageDescription
+
+let package = Package(
+  name: "AutoLayout",
+  platforms: [
+    .iOS(.v13)
+  ],
+  products: [
+    .library(
+      name: "AutoLayout",
+      targets: ["AutoLayout"]
+    )
+  ],
+  targets: [
+    .target(
+      name: "AutoLayout"
+    )
+  ]
+)

Sources/AutoLayout/LayoutConstraints+Helpers.swift

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+extension LayoutConstraints {
+  public static func merged(@LayoutConstraintsBuilder _ constraints: () -> LayoutConstraints) -> LayoutConstraints {
+    return constraints()
+  }
+}
+
+extension LayoutConstraints {
+  public mutating func merge(with constraint: LayoutConstraints) {
+    self = LayoutConstraints.merged {
+      self
+      constraint
+    }
+  }
+
+  public mutating func merge(@LayoutConstraintsBuilder with constraints: () -> LayoutConstraints) {
+    self = LayoutConstraints.merged {
+      self
+      constraints()
+    }
+  }
+}

Sources/AutoLayout/LayoutConstraints.swift

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+import UIKit
+
+/// Contains constraints of the view.
+public struct LayoutConstraints {
+  /// Top constraint.
+  public var top: NSLayoutConstraint?
+  /// Leading constraint.
+  public var leading: NSLayoutConstraint?
+  /// Bottom constraint.
+  public var bottom: NSLayoutConstraint?
+  /// Trailing constraint.
+  public var trailing: NSLayoutConstraint?
+  /// Vertical constraint.
+  public var vertical: NSLayoutConstraint?
+  /// Horizontal constraint.
+  public var horizontal: NSLayoutConstraint?
+  /// Width constraint.
+  public var width: NSLayoutConstraint?
+  /// Height constraint.
+  public var height: NSLayoutConstraint?
+
+  /// Array of all constraints.
+  public var allConstraints: [NSLayoutConstraint?] {
+    return [
+      self.top,
+      self.leading,
+      self.bottom,
+      self.trailing,
+      self.vertical,
+      self.horizontal,
+      self.width,
+      self.height
+    ]
+  }
+
+  /// Memberwise initializer.
+  public init(
+    top: NSLayoutConstraint? = nil,
+    leading: NSLayoutConstraint? = nil,
+    bottom: NSLayoutConstraint? = nil,
+    trailing: NSLayoutConstraint? = nil,
+    vertical: NSLayoutConstraint? = nil,
+    horizontal: NSLayoutConstraint? = nil,
+    width: NSLayoutConstraint? = nil,
+    height: NSLayoutConstraint? = nil
+  ) {
+    self.top = top
+    self.leading = leading
+    self.bottom = bottom
+    self.trailing = trailing
+    self.vertical = vertical
+    self.horizontal = horizontal
+    self.width = width
+    self.height = height
+  }
+
+  /// Activates existing constraints.
+  public func activateAll() {
+    self.allConstraints.forEach { $0?.isActive = true }
+  }
+
+  /// Deactivates existing constraints.
+  public func deactivateAll() {
+    self.allConstraints.forEach { $0?.isActive = false }
+  }
+}

Sources/AutoLayout/LayoutConstraintsBuilder.swift

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+@resultBuilder
+public struct LayoutConstraintsBuilder {
+  public static func buildBlock(_ constraints: LayoutConstraints...) -> LayoutConstraints {
+    constraints.reduce(into: LayoutConstraints()) { partialResult, constraints in
+      if let top = constraints.top {
+        partialResult.top = top
+      }
+      if let leading = constraints.leading {
+        partialResult.leading = leading
+      }
+      if let bottom = constraints.bottom {
+        partialResult.bottom = bottom
+      }
+      if let trailing = constraints.trailing {
+        partialResult.trailing = trailing
+      }
+      if let vertical = constraints.vertical {
+        partialResult.vertical = vertical
+      }
+      if let horizontal = constraints.horizontal {
+        partialResult.horizontal = horizontal
+      }
+      if let width = constraints.width {
+        partialResult.width = width
+      }
+      if let height = constraints.height {
+        partialResult.height = height
+      }
+    }
+  }
+}