Environment
Version 9.0 beta 6 (9M214v)
Additional Detail from JIRA
|
|
| Votes |
7 |
| Component/s |
Foundation |
| Labels |
Bug |
| Assignee |
None |
| Priority |
Medium |
md5: cc033b62e7f6826a74055dc7ea71bfeb
Issue Description:
MyHostObject owns MyObject and observes changes of it's value:
import Foundation
class MyObject: NSObject {
@objc dynamic var value: Int = 0
}
class MyHostObject: NSObject {
@objc dynamic let myObject = MyObject()
var _observation: NSKeyValueObservation?
override init() {
super.init()
_observation = observe(\.myObject.value, options: [.new]) { (myObject, change) in
print("value changed to \(change.newValue!)")
}
}
deinit {
// `myObject` is in Limbo right now, but I can still call it's methods and, hopefully, remove observation
_observation?.invalidate()
_observation = nil
}
}
var myHostObject: MyHostObject? = MyHostObject()
myHostObject = nil // crashing here with:
// *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'An instance 0x101c10290 of class issue_NSKeyValueObservation.MyHostObject was deallocated while key value observers were still registered with it. Current observation info: <NSKeyValueObservationInfo 0x101c14ed0> (
<NSKeyValueObservance 0x101c14c20: Observer: 0x101c115f0, Key path: myObject.value, Options: <New: YES, Old: NO, Prior: NO> Context: 0x0, Property: 0x101c129b0>
)'With Objective-C equivalent, MyHostObject would still be able to remove observation from myObject.
This is happening because NSKeyValueObservation holds a weak reference to an object. That weak reference turns to nil too soon. My suggestion is to use unowned or Unmanaged<MyObject> reference.
Environment
Version 9.0 beta 6 (9M214v)
Additional Detail from JIRA
md5: cc033b62e7f6826a74055dc7ea71bfeb
Issue Description:
MyHostObject owns MyObject and observes changes of it's value:
With Objective-C equivalent, MyHostObject would still be able to remove observation from myObject.
This is happening because NSKeyValueObservation holds a weak reference to an object. That weak reference turns to nil too soon. My suggestion is to use unowned or Unmanaged<MyObject> reference.