[BUG] Fixed SnapLayout not setting size constraint

- SnapLayout would not set constraint for width nor height constraint when superview not specified
  - Fixed by not relying on superview for these constraint settings
- Added more documentation
- Added debugger print messages

Author: Satinder Singh

SnapLayout.podspec

@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = 'SnapLayout'
-  s.version          = '1.0.4'
+  s.version          = '1.0.5'
   s.summary          = 'Concise API for iOS Auto Layout'
 
 s.description  = <<-DESC

SnapLayout/Classes/SnapLayout.swift

@@ -129,40 +129,55 @@ 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)
+    /// - Note: width and height are not in respect to superview, but always to self
     /// - Returns: ConstraintManager 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) -> ConstraintManager {
-        guard let view = view ?? superview else { return ConstraintManager() }
         translatesAutoresizingMaskIntoConstraints = false
         var constraintManager = ConstraintManager()
+        if let width = width {
+            constraintManager.width = widthAnchor.constraint(equalToConstant: width)
+            constraintManager.width?.isActive = true
+        }
+        if let height = height {
+            constraintManager.height = heightAnchor.constraint(equalToConstant: height)
+            constraintManager.height?.isActive = true
+        }
+        guard let view = view ?? superview else { return constraintManager }
         if let top = top {
             constraintManager.top = topAnchor.constraint(equalTo: view.topAnchor, constant: top)
+            constraintManager.top?.isActive = true
         }
         if let leading = leading {
             constraintManager.leading = leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: leading)
+            constraintManager.leading?.isActive = true
         }
         if let bottom = bottom {
             constraintManager.bottom = bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: bottom)
+            constraintManager.bottom?.isActive = true
         }
         if let trailing = trailing {
             constraintManager.trailing = trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: trailing)
-        }
-        if let width = width {
-            constraintManager.width = widthAnchor.constraint(equalToConstant: width)
-        }
-        if let height = height {
-            constraintManager.height = heightAnchor.constraint(equalToConstant: height)
+            constraintManager.trailing?.isActive = true
         }
         if let centerX = centerX, centerX {
             constraintManager.centerX = centerXAnchor.constraint(equalTo: view.centerXAnchor)
+            constraintManager.centerX?.isActive = true
         }
         if let centerY = centerY, centerY {
             constraintManager.centerY = centerYAnchor.constraint(equalTo: view.centerYAnchor)
+            constraintManager.centerY?.isActive = true
+        }
+        let inActiveCount = [constraintManager.width, constraintManager.height, constraintManager.top, constraintManager.leading,
+                           constraintManager.bottom, constraintManager.trailing, constraintManager.centerX,
+                           constraintManager.centerY].filter ({ $0?.isActive == false }).count
+        if inActiveCount == 0 {
+            print("SnapLayout Error - No constraint was applied for view: \(String(describing: view))")
         }
-        [constraintManager.top, constraintManager.leading, constraintManager.bottom, constraintManager.trailing,
-         constraintManager.width, constraintManager.height, constraintManager.centerX, constraintManager.centerY].forEach { $0?.isActive = true }
         return constraintManager
     }
 
@@ -207,7 +222,10 @@ public extension UIView {
     /// - Returns: ConstraintManager holding all the values associated with constraints
     @discardableResult
     func snapWidth(to view: UIView? = nil, multiplier: CGFloat = 1) -> ConstraintManager {
-        guard let view = view ?? superview else { return ConstraintManager() }
+        guard let view = view ?? superview else {
+            print("SnapLayout Error - width constraint not applied")
+            return ConstraintManager()
+        }
         translatesAutoresizingMaskIntoConstraints = false
         let constraintManager = ConstraintManager()
         constraintManager.width = widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: multiplier)
@@ -236,7 +254,10 @@ public extension UIView {
     /// - Returns: ConstraintManager holding all the values associated with constraints
     @discardableResult
     func snapHeight(to view: UIView? = nil, multiplier: CGFloat = 1) -> ConstraintManager {
-        guard let view = view ?? superview else { return ConstraintManager() }
+        guard let view = view ?? superview else {
+            print("SnapLayout Error - height constraint not applied")
+            return ConstraintManager()
+        }
         translatesAutoresizingMaskIntoConstraints = false
         let constraintManager =  ConstraintManager()
         constraintManager.height = heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: multiplier)