[FEATURE] centerX and centerY constraints now support offset

- Offset can be applied from centerX and/or centerY
- Updated ReadME with changes

Example/Podfile.lock

@@ -1,5 +1,5 @@
 PODS:
-  - SnapLayout (1.3.0)
+  - SnapLayout (1.4.1)
 
 DEPENDENCIES:
   - SnapLayout (from `../`)
@@ -9,7 +9,7 @@ EXTERNAL SOURCES:
     :path: "../"
 
 SPEC CHECKSUMS:
-  SnapLayout: 80268468432382a44ba9277365d42b4acb4932d1
+  SnapLayout: ac48d267164271e7bbcbf391e29295d384ac0cbb
 
 PODFILE CHECKSUM: f6cd245470fd9f107dd94e8ef9bffeaa3467d0af
 

Example/SnapLayout/ViewController.swift

@@ -51,7 +51,7 @@ internal final class ViewController: UIViewController {
         snapLabel.font = UIFont(name: "Avenir-Book", size: 24)
         containerView.addSubview(snapLabel)
         // label will be below emojiTextView and aligned horizontally relative to super view
-        snapLabel.snap(topView: emojiLabel).snap(centerX: true)
+        snapLabel.snap(topView: emojiLabel).snap(centerX: 0)
     }
 
     /**

Example/SnapLayout_ExampleTests/SnapConfigTests.swift

@@ -20,8 +20,8 @@ class SnapConfigTests: XCTestCase {
         let trailingConstant = CGFloat(24)
         let widthConstant = CGFloat(32)
         let heightConstant = CGFloat(64)
-        let centerXConstant = true
-        let centerYConstant = true
+        let centerXConstant = CGFloat(0)
+        let centerYConstant = CGFloat(0)
         let snapConfig = SnapConfig(top: topConstant,
                                     leading: leadingConstant,
                                     bottom: bottomConstant,

Example/SnapLayout_ExampleTests/SnapManagerTests.swift

@@ -21,8 +21,8 @@ class SnapManagerTests: BaseTestCase {
         let trailingConstant = CGFloat(24)
         let widthConstant = CGFloat(32)
         let heightConstant = CGFloat(64)
-        let centerXConstant = true
-        let centerYConstant = true
+        let centerXConstant = CGFloat(0)
+        let centerYConstant = CGFloat(0)
         let snapManager = childView.snap(top: topConstant,
                                     leading: leadingConstant,
                                     bottom: bottomConstant,
@@ -45,9 +45,9 @@ class SnapManagerTests: BaseTestCase {
         XCTAssertNotNil(snapManager.height)
         XCTAssertEqual(snapManager.height!.constant, heightConstant)
         XCTAssertNotNil(snapManager.centerX)
-        XCTAssertEqual(snapManager.centerX!.constant, 0)
+        XCTAssertEqual(snapManager.centerX!.constant, centerXConstant)
         XCTAssertNotNil(snapManager.centerY)
-        XCTAssertEqual(snapManager.centerY!.constant, 0)
+        XCTAssertEqual(snapManager.centerY!.constant, centerYConstant)
     }
 
     /// Test Snap Manager Constructor with a view who does not have a superview
@@ -114,8 +114,8 @@ class SnapManagerTests: BaseTestCase {
         let trailingConstant = CGFloat(24)
         let widthConstant = CGFloat(32)
         let heightConstant = CGFloat(64)
-        let centerXConstant = true
-        let centerYConstant = true
+        let centerXConstant = CGFloat(0)
+        let centerYConstant = CGFloat(0)
         let snapConfig = SnapConfig(top: topConstant,
                                     leading: leadingConstant,
                                     bottom: bottomConstant,
@@ -139,9 +139,9 @@ class SnapManagerTests: BaseTestCase {
         XCTAssertNotNil(snapManager.height)
         XCTAssertEqual(snapManager.height!.constant, heightConstant)
         XCTAssertNotNil(snapManager.centerX)
-        XCTAssertEqual(snapManager.centerX!.constant, 0)
+        XCTAssertEqual(snapManager.centerX!.constant, centerXConstant)
         XCTAssertNotNil(snapManager.centerY)
-        XCTAssertEqual(snapManager.centerY!.constant, 0)
+        XCTAssertEqual(snapManager.centerY!.constant, centerYConstant)
     }
 
     /// Test Snap Manager Config Constructor when used with chaining.
@@ -153,8 +153,8 @@ class SnapManagerTests: BaseTestCase {
         let trailingConstant = CGFloat(24)
         let widthConstant = CGFloat(32)
         let heightConstant = CGFloat(64)
-        let centerXConstant = true
-        let centerYConstant = true
+        let centerXConstant = CGFloat(0)
+        let centerYConstant = CGFloat(0)
         let snapConfig = SnapConfig(top: topConstant,
                                     leading: leadingConstant,
                                     bottom: bottomConstant,
@@ -177,7 +177,9 @@ class SnapManagerTests: BaseTestCase {
         XCTAssertNotNil(snapManager.height)
         XCTAssertEqual(snapManager.height!.constant, heightConstant)
         XCTAssertNotNil(snapManager.centerX)
+        XCTAssertEqual(snapManager.centerX!.constant, centerXConstant)
         XCTAssertNotNil(snapManager.centerY)
+        XCTAssertEqual(snapManager.centerY!.constant, centerYConstant)
     }
 
     /// Tests Snap Manager width during chaining

README.md

@@ -18,17 +18,18 @@ Lets use a real world example. Lets say the following view needs to be added. It
 
 ```swift
 squareView.translatesAutoresizingMaskIntoConstraints = false
-squareView.centerXAnchor.constraint(equalTo: squareSuperview.centerXAnchor)
-squareView.centerYAnchor.constraint(equalTo: squareSuperview.centerYAnchor)
 squareView.widthAnchor.constraint(equalToConstant: 50)
 squareView.heightAnchor.constraint(equalToConstant: 50)
+squareView.centerXAnchor.constraint(equalTo: squareSuperview.centerXAnchor, constant: 0)
+squareView.centerYAnchor.constraint(equalTo: squareSuperview.centerYAnchor, constant: 0)
 ```
 
 SnapLayout:
 
 ```swift
-squareView.snap(centerX: true, centerY: true, width: 50, height: 50)
+squareView.snap(width: 50, height: 50, centerX: 0, centerY: 0)
 ```
+SnapLayout handles `translatesAutoresizingMaskIntoConstraints` and references the superview of `squareView` when applying constraints. Built to be flexible, yet readable.
 
 ## Setup
 ### Requirements
@@ -62,7 +63,7 @@ pod "SnapLayout"
 
 ### [`UIView`](SnapLayout/Classes/SnapLayout.swift) extension methods
 ```swift
-func snap(to view: UIView? = nil, top: CGFloat? = nil, leading: CGFloat? = nil, bottom: CGFloat? = nil, trailing: CGFloat? = nil, width: CGFloat? = nil, height: CGFloat? = nil, centerX: Bool? = nil, centerY: Bool? = nil) -> ConstraintManager
+func snap(to view: UIView? = nil, top: CGFloat? = nil, leading: CGFloat? = nil, bottom: CGFloat? = nil, trailing: CGFloat? = nil, width: CGFloat? = nil, height: CGFloat? = nil, centerX: CGFloat? = nil, centerY: CGFloat? = nil) -> ConstraintManager
 func snap(to view: UIView? = nil, constants: SnapConfig) -> SnapManager
 func snapWidth(to view: UIView, multiplier: CGFloat = 1) -> SnapManager
 func snapHeight(to view: UIView, multiplier: CGFloat = 1) -> SnapManager
@@ -99,7 +100,7 @@ Snap calls may also be chained and will continue to return a `SnapManager`.
 A `SnapConfig ` struct is also available where a developer may list all of their constraint constants beforehand and provide this type to the snap method argument.
 
 ```swift
-let buttonSnapConfig = SnapConfig(top: 50, leading: 50, trailing: 50, width: 30, centerX: true)
+let buttonSnapConfig = SnapConfig(top: 50, leading: 50, trailing: 50, width: 30, centerX: 0)
 let buttonSnapConfig = button.snap(constants: buttonConstraintConstants)
 ```
 

SnapLayout.podspec

@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = 'SnapLayout'
-  s.version          = '1.4.1'
+  s.version          = '1.5.0'
   s.summary          = 'Concise API for iOS Auto Layout'
 
 s.description  = <<-DESC

SnapLayout/Classes/SnapConfig.swift

@@ -27,11 +27,11 @@ public struct SnapConfig {
     /// Constant value associated with height constraint. If nil, no constraint is applied.
     public var height: CGFloat?
 
-    /// Value associated with centerX constraint. Constraint only applied if true.
-    public var centerX: Bool?
+    /// Value associated with centerX constraint. If nil, no constraint is applied.
+    public var centerX: CGFloat?
 
-    /// Value associated with centerY constraint. Constraint only applied if true.
-    public var centerY: Bool?
+    /// Value associated with centerY constraint. If nil, no constraint is applied.
+    public var centerY: CGFloat?
 
     /// Constant value associated with zero for top, leading, bottom, and trailing.
     /// No width, height, centerX nor centerY constraint is applied.
@@ -46,11 +46,11 @@ public struct SnapConfig {
     ///   - trailing: Constant to apply from trailingAnchor  (if nil, not applied)
     ///   - width: Constant value associated with width constraint. If nil, no constraint is applied.
     ///   - height: Constant to apply from heightAnchor  (if nil, not applied)
-    ///   - centerX: Boolean determining if centerX should be applied  (if nil, not applied)
-    ///   - centerY: Boolean determining if centerY should be applied  (if nil, not applied)
+    ///   - centerX: Constant offset to apply from centerXAnchor  (if nil, not applied)
+    ///   - centerY: Constant offset to apply from centerXAnchor  (if nil, not applied)
     public init(top: CGFloat? = nil, leading: CGFloat? = nil, bottom: CGFloat? = nil,
                 trailing: CGFloat? = nil, width: CGFloat? = nil, height: CGFloat? = nil,
-                centerX: Bool? = nil, centerY: Bool? = nil) {
+                centerX: CGFloat? = nil, centerY: CGFloat? = nil) {
         self.top = top
         self.leading = leading
         self.bottom = bottom

SnapLayout/Classes/SnapLayout.swift

@@ -21,14 +21,14 @@ public extension UIView {
     ///   - trailing: Constant to apply from trailingAnchor  (if nil, not applied)
     ///   - width: Constant to apply from widthAnchor  (if nil, not applied)
     ///   - height: Constant to apply from heightAnchor  (if nil, not applied)
-    ///   - centerX: Boolean determining if centerX should be applied  (if nil, not applied)
-    ///   - centerY: Boolean determining if centerY should be applied  (if nil, not applied)
+    ///   - centerX: Constant offset to apply from centerXAnchor  (if nil, not applied)
+    ///   - centerY: Constant offset to apply from centerXAnchor  (if nil, not applied)
     /// - Note: width and height are not in respect to superview, but always to self
     /// - Returns: SnapManager holding all the values associated with constraints
     @discardableResult
     func snap(to view: UIView? = nil, top: CGFloat? = nil, leading: CGFloat? = nil, bottom: CGFloat? = nil,
-              trailing: CGFloat? = nil, width: CGFloat? = nil, height: CGFloat? = nil, centerX: Bool? = nil,
-              centerY: Bool? = nil) -> SnapManager {
+              trailing: CGFloat? = nil, width: CGFloat? = nil, height: CGFloat? = nil, centerX: CGFloat? = nil,
+              centerY: CGFloat? = nil) -> SnapManager {
         translatesAutoresizingMaskIntoConstraints = false
         var snapManager = SnapManager(view: self)
         if let width = width {
@@ -61,12 +61,12 @@ public extension UIView {
             snapManager.trailing = view.trailingAnchor.constraint(equalTo: trailingAnchor, constant: trailing)
             snapManager.trailing?.isActive = true
         }
-        if let centerX = centerX, centerX {
-            snapManager.centerX = centerXAnchor.constraint(equalTo: view.centerXAnchor)
+        if let centerX = centerX {
+            snapManager.centerX = centerXAnchor.constraint(equalTo: view.centerXAnchor, constant: centerX)
             snapManager.centerX?.isActive = true
         }
-        if let centerY = centerY, centerY {
-            snapManager.centerY = centerYAnchor.constraint(equalTo: view.centerYAnchor)
+        if let centerY = centerY {
+            snapManager.centerY = centerYAnchor.constraint(equalTo: view.centerYAnchor, constant: centerY)
             snapManager.centerY?.isActive = true
         }
         let inActiveCount = [snapManager.width, snapManager.height, snapManager.top, snapManager.leading,

SnapLayout/Classes/SnapManager.swift

@@ -62,8 +62,8 @@ public class SnapManager {
     /// - Returns: SnapManager holding all the values associated with constraints
     @discardableResult
     public func snap(to view: UIView? = nil, top: CGFloat? = nil, leading: CGFloat? = nil, bottom: CGFloat? = nil,
-                     trailing: CGFloat? = nil, width: CGFloat? = nil, height: CGFloat? = nil, centerX: Bool? = nil,
-                     centerY: Bool? = nil) -> SnapManager {
+                     trailing: CGFloat? = nil, width: CGFloat? = nil, height: CGFloat? = nil, centerX: CGFloat? = nil,
+                     centerY: CGFloat? = nil) -> SnapManager {
         guard let weakView = weakView else {
             print("SnapLayout Error - Cannot apply constraint upon a view that is not retained")
             return SnapManager()