[SR-914] Swift needs @dynamic support

[an0]

Previous ID	SR-914
Radar	rdar://problem/22595617
Original Reporter	@an0
Type	Improvement

Additional Detail from JIRA

Votes	0
Component/s
Labels	Improvement
Assignee	None
Priority	Medium

md5: 40a8c6b62f2414b3d821607799557a15

Issue Description:

@dynamic properties are necessary for some Cocoa frameworks. One example is Core Data managed objects subclasses. Currently Swift uses a special attribute @NSManaged for that. “However, unlike @dynamic, the @NSManaged attribute is available only for Core Data support.”

It will be great if Core Data is the only use case of @dynamic. But that’s not true. For example, Core Animation layer subclasses also need @dynamic properties to implement custom animations: https://forums.developer.apple.com/thread/12656. So my suggestion is that @NSManaged should be replaced by a more general attribute matching @dynamic.