core-data - CoreData addObserver NSKeyValueChangeInsertion

Question

有没有办法获取在 NSManagedObject 上使用 addObserver:forKeyPath:options:context: 和选项 NSKeyValueChangeInsertion 添加的对象>?

Answer 1

是的。来自 observeValueForKeyPath:ofObject:change:context: 的文档:

change A dictionary that describes the changes that have been made to the value of the property at the key path keyPath relative to object. Entries are described in “Keys used by the change dictionary.”

再往下:

NSKeyValueChangeKindKey An NSNumber object that contains a value corresponding to one of the NSKeyValueChangeKindKey enumerations, indicating what sort of change has occurred.

NSKeyValueChangeIndexesKey If the value of the NSKeyValueChangeKindKey entry is NSKeyValueChangeInsertion, NSKeyValueChangeRemoval, or NSKeyValueChangeReplacement, the value of this key is an NSIndexSet object that contains the indexes of the inserted, removed, or replaced objects.