Added leading and trailing support

Sources/iOS/Layout.swift

@@ -124,6 +124,26 @@ public extension Layout {
   }
   
   /**
+   Constraints leading of the view to its parent's.
+   - Parameter _ offset: A CGFloat offset.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func leading(_ offset: CGFloat = 0) -> Layout {
+    return constraint(.leading, constant: offset)
+  }
+  
+  /**
+   Constraints trailing of the view to its parent.
+   - Parameter _ offset: A CGFloat offset.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func trailing(_ offset: CGFloat = 0) -> Layout {
+    return constraint(.trailing, constant: -offset)
+  }
+  
+  /**
    Constraints bottom of the view to its parent's.
    - Parameter _ offset: A CGFloat offset.
    - Returns: A Layout instance to allow chaining.
@@ -189,6 +209,61 @@ public extension Layout {
   }
   
   /**
+   Constraints top-leading of the view to its parent's.
+   - Parameter top: A CGFloat offset for top.
+   - Parameter leading: A CGFloat offset for leading.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func topLeading(top: CGFloat = 0, leading: CGFloat = 0) -> Layout {
+    return constraint(.topLeading, constants: top, leading)
+  }
+  
+  /**
+   Constraints top-trailing of the view to its parent's.
+   - Parameter top: A CGFloat offset for top.
+   - Parameter trailing: A CGFloat offset for trailing.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func topTrailing(top: CGFloat = 0, trailing: CGFloat = 0) -> Layout {
+    return constraint(.topTrailing, constants: top, -trailing)
+  }
+  
+  /**
+   Constraints bottom-leading of the view to its parent's.
+   - Parameter bottom: A CGFloat offset for bottom.
+   - Parameter leading: A CGFloat offset for leading.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func bottomLeading(bottom: CGFloat = 0, leading: CGFloat = 0) -> Layout {
+    return constraint(.bottomLeading, constants: -bottom, leading)
+  }
+  
+  /**
+   Constraints bottom-trailing of the view to its parent's.
+   - Parameter bottom: A CGFloat offset for bottom.
+   - Parameter trailing: A CGFloat offset for trailing.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func bottomTrailing(bottom: CGFloat = 0, trailing: CGFloat = 0) -> Layout {
+    return constraint(.bottomTrailing, constants: -bottom, -trailing)
+  }
+  
+  /**
+   Constraints leading and trailing of the view to its parent's.
+   - Parameter leading: A CGFloat offset for leading.
+   - Parameter trailing: A CGFloat offset for trailing.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func leadingTrailing(leading: CGFloat = 0, trailing: CGFloat = 0) -> Layout {
+    return constraint(.leadingTrailing, constants: leading, -trailing)
+  }
+  
+  /**
    Constraints top and bottom of the view to its parent's.
    - Parameter top: A CGFloat offset for top.
    - Parameter bottom: A CGFloat offset for bottom.
@@ -321,6 +396,28 @@ public extension Layout {
   }
   
   /**
+   Constraints leading of the view to the given anchor.
+   - Parameter _ anchor: A LayoutAnchorable.
+   - Parameter _ offset: A CGFloat offset.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func leading(_ anchor: LayoutAnchorable, _ offset: CGFloat = 0) -> Layout {
+    return constraint(.leading, to: anchor, constant: offset)
+  }
+  
+  /**
+   Constraints trailing of the view to the given anchor.
+   - Parameter _ anchor: A LayoutAnchorable.
+   - Parameter _ offset: A CGFloat offset.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func trailing(_ anchor: LayoutAnchorable, _ offset: CGFloat = 0) -> Layout {
+    return constraint(.trailing, to: anchor, constant: -offset)
+  }
+  
+  /**
    Constraints bottom of the view to the given anchor.
    - Parameter _ anchor: A LayoutAnchorable.
    - Parameter _ offset: A CGFloat offset.
@@ -332,6 +429,66 @@ public extension Layout {
   }
   
   /**
+   Constraints top-leading of the view to the given anchor.
+   - Parameter _ anchor: A LayoutAnchorable.
+   - Parameter top: A CGFloat offset for top.
+   - Parameter leading: A CGFloat offset for leading.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func topLeading(_ anchor: LayoutAnchorable, top: CGFloat = 0, leading: CGFloat = 0) -> Layout {
+    return constraint(.topLeading, to: anchor, constants: top, leading)
+  }
+  
+  /**
+   Constraints top-trailing of the view to the given anchor.
+   - Parameter _ anchor: A LayoutAnchorable.
+   - Parameter top: A CGFloat offset for top.
+   - Parameter trailing: A CGFloat offset for trailing.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func topTrailing(_ anchor: LayoutAnchorable, top: CGFloat = 0, trailing: CGFloat = 0) -> Layout {
+    return constraint(.topTrailing, to: anchor, constants: top, -trailing)
+  }
+  
+  /**
+   Constraints bottom-leading of the view to the given anchor.
+   - Parameter _ anchor: A LayoutAnchorable.
+   - Parameter bottom: A CGFloat offset for bottom.
+   - Parameter leading: A CGFloat offset for leading.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func bottomLeading(_ anchor: LayoutAnchorable, bottom: CGFloat = 0, leading: CGFloat = 0) -> Layout {
+    return constraint(.bottomLeading, to: anchor, constants: -bottom, leading)
+  }
+  
+  /**
+   Constraints bottom-trailing of the view to the given anchor.
+   - Parameter _ anchor: A LayoutAnchorable.
+   - Parameter bottom: A CGFloat offset for bottom.
+   - Parameter trailing: A CGFloat offset for trailing.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func bottomTrailing(_ anchor: LayoutAnchorable, bottom: CGFloat = 0, trailing: CGFloat = 0) -> Layout {
+    return constraint(.bottomTrailing, to: anchor, constants: -bottom, -trailing)
+  }
+  
+  /**
+   Constraints leading and trailing of the view to the given anchor.
+   - Parameter _ anchor: A LayoutAnchorable.
+   - Parameter leading: A CGFloat offset for leading.
+   - Parameter trailing: A CGFloat offset for trailing.
+   - Returns: A Layout instance to allow chaining.
+   */
+  @discardableResult
+  func leadingTrailing(_ anchor: LayoutAnchorable, leading: CGFloat = 0, trailing: CGFloat = 0) -> Layout {
+    return constraint(.leadingTrailing, to: anchor, constants: leading, -trailing)
+  }
+  
+  /**
    Constraints top-left of the view to the given anchor.
    - Parameter _ anchor: A LayoutAnchorable.
    - Parameter top: A CGFloat offset for top.

Sources/iOS/LayoutAnchor.swift

@@ -76,6 +76,16 @@ public extension LayoutAnchor {
     return anchor(.right)
   }
   
+  /// A layout anchor representing leading of the view.
+  var leading: LayoutAnchor {
+    return anchor(.leading)
+  }
+  
+  /// A layout anchor representing trailing of the view.
+  var trailing: LayoutAnchor {
+    return anchor(.trailing)
+  }
+  
   /// A layout anchor representing top-left of the view.
   var topLeft: LayoutAnchor {
     return acnhor(.topLeft)
@@ -96,6 +106,26 @@ public extension LayoutAnchor {
     return acnhor(.bottomRight)
   }
   
+  /// A layout anchor representing top-leading of the view.
+  var topLeading: LayoutAnchor {
+    return acnhor(.topLeading)
+  }
+  
+  /// A layout anchor representing top-trailing of the view.
+  var topTrailing: LayoutAnchor {
+    return acnhor(.topTrailing)
+  }
+  
+  /// A layout anchor representing bottom-leading of the view.
+  var bottomLeading: LayoutAnchor {
+    return acnhor(.bottomLeading)
+  }
+  
+  /// A layout anchor representing bottom-trailing of the view.
+  var bottomTrailing: LayoutAnchor {
+    return acnhor(.bottomTrailing)
+  }
+  
   /// A layout anchor representing top and bottom of the view.
   var topBottom: LayoutAnchor {
     return acnhor(.topBottom)
@@ -106,6 +136,11 @@ public extension LayoutAnchor {
     return acnhor(.leftRight)
   }
   
+  /// A layout anchor representing leading and trailing of the view.
+  var leadingTrailing: LayoutAnchor {
+    return acnhor(.leadingTrailing)
+  }
+  
   /// A layout anchor representing center of the view.
   var center: LayoutAnchor {
     return acnhor(.center)

Sources/iOS/LayoutAttribute.swift

@@ -59,6 +59,31 @@ internal extension Array where Element == LayoutAttribute {
     return [.left, .right]
   }
   
+  /// A LayoutAttribute array containing top and leading.
+  static var topLeading: [LayoutAttribute] {
+    return [.top, .leading]
+  }
+  
+  /// A LayoutAttribute array containing top and trailing.
+  static var topTrailing: [LayoutAttribute] {
+    return [.top, .trailing]
+  }
+  
+  /// A LayoutAttribute array containing bottom and leading.
+  static var bottomLeading: [LayoutAttribute] {
+    return [.bottom, .leading]
+  }
+  
+  /// A LayoutAttribute array containing bottom and trailing.
+  static var bottomTrailing: [LayoutAttribute] {
+    return [.bottom, .trailing]
+  }
+  
+  /// A LayoutAttribute array containing left and trailing.
+  static var leadingTrailing: [LayoutAttribute] {
+    return [.leading, .trailing]
+  }
+  
   /// A LayoutAttribute array containing top and bottom.
   static var topBottom: [LayoutAttribute] {
     return [.top, .bottom]