Fix Memory Leaks

Source/Constraint.swift

@@ -27,7 +27,8 @@
     import AppKit
 #endif
 
-public class Constraint {
+@objc(SnapKitConstraint)
+public final class Constraint : NSObject {
     
     internal let sourceLocation: (String, UInt)
     internal let label: String?
@@ -67,6 +68,7 @@ public class Constraint {
         self.constant = constant
         self.priority = priority
         self.layoutConstraints = []
+        super.init()
         
         // get attributes
         let layoutFromAttributes = self.from.attributes.layoutAttributes
@@ -260,7 +262,7 @@ public class Constraint {
             }
             
             for layoutConstraint in layoutConstraints {
-                let existingLayoutConstraint = existingLayoutConstraints.first { $0.canUpdate(constraint: layoutConstraint) }
+                let existingLayoutConstraint = existingLayoutConstraints.first { $0 == layoutConstraint }
                 guard let updateLayoutConstraint = existingLayoutConstraint else {
                     fatalError("Updated constraint could not find existing matching constraint to update: \(layoutConstraint)")
                 }

Source/ConstraintDescription.swift

@@ -45,7 +45,7 @@ public class ConstraintDescription {
               let sourceLocation = self.sourceLocation else {
             return nil
         }
-        let from = ConstraintItem(target: self.item as AnyObject, attributes: self.attributes)
+        let from = ConstraintItem(target: self.item, attributes: self.attributes)
         
         return Constraint(
             from: from,

Source/ConstraintItem.swift

@@ -28,7 +28,7 @@
 #endif
 
 
-public class ConstraintItem : Equatable {
+public final class ConstraintItem {
     
     internal weak var target: AnyObject?
     internal let attributes: ConstraintAttributes

Source/ConstraintMaker.swift

@@ -160,20 +160,42 @@ public class ConstraintMaker {
     internal static func prepareConstraints(item: LayoutConstraintItem, closure: (_ make: ConstraintMaker) -> Void) -> [Constraint] {
         let maker = ConstraintMaker(item: item)
         closure(maker)
-        let constraints = maker.descriptions
-            .map { $0.constraint }
-            .filter { $0 != nil }
-            .map { $0! }
+        var constraints: [Constraint] = []
+        for description in maker.descriptions {
+            guard let constraint = description.constraint else {
+                continue
+            }
+            constraints.append(constraint)
+        }
         return constraints
     }
     
     internal static func makeConstraints(item: LayoutConstraintItem, closure: (_ make: ConstraintMaker) -> Void) {
         let maker = ConstraintMaker(item: item)
         closure(maker)
-        let constraints = maker.descriptions
-            .map { $0.constraint }
-            .filter { $0 != nil }
-            .map { $0! }
+        var constraints: [Constraint] = []
+        for description in maker.descriptions {
+            
+            guard let relation = description.relation,
+                let related = description.related,
+                let sourceLocation = description.sourceLocation else {
+                    continue
+            }
+            let from = ConstraintItem(target: description.item, attributes: description.attributes)
+            
+            let constraint = Constraint(
+                from: from,
+                to: related,
+                relation: relation,
+                sourceLocation: sourceLocation,
+                label: description.label,
+                multiplier: description.multiplier,
+                constant: description.constant,
+                priority: description.priority
+            )
+            
+            constraints.append(constraint)
+        }
         for constraint in constraints {
             constraint.activateIfNeeded(updatingExisting: false)
         }
@@ -192,10 +214,13 @@ public class ConstraintMaker {
         
         let maker = ConstraintMaker(item: item)
         closure(maker)
-        let constraints = maker.descriptions
-            .map { $0.constraint }
-            .filter { $0 != nil }
-            .map { $0! }
+        var constraints: [Constraint] = []
+        for description in maker.descriptions {
+            guard let constraint = description.constraint else {
+                continue
+            }
+            constraints.append(constraint)
+        }
         for constraint in constraints {
             constraint.activateIfNeeded(updatingExisting: true)
         }

Source/LayoutConstraintItem.swift

@@ -59,33 +59,33 @@ extension LayoutConstraintItem {
         return nil
     }
     internal var constraints: [Constraint] {
-        return self.constraintsHashTable.allObjects
+        return self.constraintsSet.allObjects as! [Constraint]
     }
     
     internal func add(constraints: [Constraint]) {
-        let hashTable = self.constraintsHashTable
+        let constraintsSet = NSMutableSet()
         for constraint in constraints {
-            hashTable.add(constraint)
+            constraintsSet.add(constraint)
         }
     }
     
     internal func remove(constraints: [Constraint]) {
-        let hashTable = self.constraintsHashTable
+        let constraintsSet = NSMutableSet()
         for constraint in constraints {
-            hashTable.remove(constraint)
+            constraintsSet.remove(constraint)
         }
     }
     
-    private var constraintsHashTable: NSHashTable<Constraint> {
-        let constraints: NSHashTable<Constraint>
+    private var constraintsSet: NSMutableSet {
+        let constraintsSet: NSMutableSet
         
-        if let existing = objc_getAssociatedObject(self, &constraintsKey) as? NSHashTable<Constraint> {
-            constraints = existing
+        if let existing = objc_getAssociatedObject(self, &constraintsKey) as? NSMutableSet {
+            constraintsSet = existing
         } else {
-            constraints = NSHashTable<Constraint>()
-            objc_setAssociatedObject(self, &constraintsKey, constraints, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
+            constraintsSet = NSMutableSet()
+            objc_setAssociatedObject(self, &constraintsKey, constraintsSet, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
         }
-        return constraints
+        return constraintsSet
         
     }