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Merge pull request #24356 from zetasq/zetasq-fix-KVO

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This commit is contained in:
swift-ci
2019-07-25 15:14:18 -07:00
committed by GitHub
parent 3fdb42f463 45112229b6
commit f34ef5db85
2 changed files with 61 additions and 2 deletions
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36
stdlib/public/Darwin/Foundation/NSObject.swift
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@@ -233,6 +233,17 @@ public class NSKeyValueObservation : NSObject {
}
}
// Used for type-erase Optional type
private protocol _OptionalForKVO {
static func _castForKVO(_ value: Any) -> Any?
}
extension Optional: _OptionalForKVO {
static func _castForKVO(_ value: Any) -> Any? {
return value as? Wrapped
}
}
extension _KeyValueCodingAndObserving {
///when the returned NSKeyValueObservation is deinited or invalidated, it will stop observing
@@ -242,9 +253,30 @@ extension _KeyValueCodingAndObserving {
changeHandler: @escaping (Self, NSKeyValueObservedChange<Value>) -> Void)
-> NSKeyValueObservation {
return NSKeyValueObservation(object: self as! NSObject, keyPath: keyPath, options: options) { (obj, change) in
let converter = { (changeValue: Any?) -> Value? in
if let optionalType = Value.self as? _OptionalForKVO.Type {
// Special logic for keyPath having a optional target value. When the keyPath referencing a nil value, the newValue/oldValue should be in the form .some(nil) instead of .none
// Solve https://bugs.swift.org/browse/SR-6066
// NSNull is used by KVO to signal that the keyPath value is nil.
// If Value == Optional<T>.self, We will get nil instead of .some(nil) when casting Optional(<null>) directly.
// To fix this behavior, we will eliminate NSNull first, then cast the transformed value.
if let unwrapped = changeValue {
// We use _castForKVO to cast first.
// If Value != Optional<NSNull>.self, the NSNull value will be eliminated.
let nullEliminatedValue = optionalType._castForKVO(unwrapped) as Any
let transformedOptional: Any? = nullEliminatedValue
return transformedOptional as? Value
}
}
return changeValue as? Value
}
let notification = NSKeyValueObservedChange(kind: change.kind,
newValue: change.newValue as? Value,
oldValue: change.oldValue as? Value,
newValue: converter(change.newValue),
oldValue: converter(change.oldValue),
indexes: change.indexes,
isPrior: change.isPrior)
changeHandler(obj as! Self, notification)

27
test/stdlib/KVOKeyPaths.swift
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@@ -191,3 +191,30 @@ print("keyPath == \\Sortable1.name:", descriptor.keyPath == \Sortable1.name)
// CHECK-51-LABEL: creating NSSortDescriptor
// CHECK-51-NEXT: keyPath == \Sortable1.name: true
//===----------------------------------------------------------------------===//
// Test keyPath with optional value has correct oldValue/newValue behavior
//===----------------------------------------------------------------------===//
class TestClassForOptionalKeyPath : NSObject {
// Should not use NSObject? as object type
@objc dynamic var optionalObject: String?
}
let testObjectForOptionalKeyPath = TestClassForOptionalKeyPath()
print("observe keyPath with optional value")
let optionalKeyPathObserver = testObjectForOptionalKeyPath.observe(\.optionalObject, options: [.initial, .old, .new]) { (_, change) in
Swift.print("oldValue = \(change.oldValue as String??), newValue = \(change.newValue as String??)")
}
testObjectForOptionalKeyPath.optionalObject = nil
testObjectForOptionalKeyPath.optionalObject = "foo"
// CHECK-LABEL: observe keyPath with optional value
// CHECK-NEXT: oldValue = Optional(nil), newValue = Optional(nil)
// CHECK-NEXT: oldValue = Optional(nil), newValue = Optional(nil)
// CHECK-NEXT: oldValue = Optional(nil), newValue = Optional(Optional("foo"))