Allow removing subscriptions by owner

Observable-Swift/Event.swift

@@ -58,6 +58,10 @@ public struct Event<T>: UnownableEvent {
         return add(SubscriptionType(owner: owner, handler: handler))
     }
 
+    public mutating func remove(owner owner : AnyObject) {
+        _subscriptions = _subscriptions.filter { $0.owner !== owner }
+    }
+
     public mutating func unshare() {
 //        _subscriptions.unshare()
     }

Observable-Swift/EventReference.swift

@@ -38,6 +38,10 @@ public class EventReference<T>: OwnableEvent {
         return event.add(owner: owner, handler)
     }
 
+    public func remove(owner owner : AnyObject) {
+        return event.remove(owner: owner)
+    }
+
     public convenience init() {
         self.init(event: Event<T>())
     }
@@ -46,4 +50,4 @@ public class EventReference<T>: OwnableEvent {
         self.event = event
     }
 
-}
+}

Observable-Swift/EventSubscription.swift

@@ -22,6 +22,8 @@ public class EventSubscription<T> {
     public typealias HandlerType = T -> ()
 
     internal var _valid : () -> Bool
+
+    internal weak var owner : AnyObject?
 
     /// Handler to be caled when value changes.
     internal var handler : HandlerType
@@ -54,6 +56,7 @@ public class EventSubscription<T> {
         } else {
             _valid = { [weak o] in o != nil }
         }
+        owner = o
         handler = h
     }
 
@@ -66,4 +69,4 @@ public class EventSubscription<T> {
     public func removeOwnedObject(o: AnyObject) {
         _owned = _owned.filter{ $0 !== o }
     }
-}
+}

Observable-SwiftTests/ObservableTests.swift

@@ -131,6 +131,20 @@ class ObservableTests: XCTestCase {
         XCTAssertEqual(y, 5, "Should not update after removed")
     }
 
+    func testRemoveByOwner() {
+        var x = Observable(0)
+        var y = 0
+
+        x.afterChange.add(owner:self) { _ in y += 1 }
+
+        for i in 0..<5 { x <- i }
+
+        x.afterChange.remove(owner:self)
+
+        for i in 0..<5 { x <- i }
+        XCTAssertEqual(y, 5, "Should not update after removed")
+    }
+
     func testValueAfterCopy() {
         let original = Observable(0)
         var copy = makeCopy(original)