Instance Property インスタンスプロパティ

old

A Boolean value that indicates when the observed progress object invokes the publish method before you subscribe to it. あるブール値、それは監視された進捗オブジェクトが出版メソッドをあなたがそれを定期購買する前に発動する場合を指し示します。

Declaration 宣言

@property(readonly, getter=isOld) BOOL old;

Discussion 議論

The publish and subscribe mechanism is generally level-triggered, in that when you invoke addSubscriberForFileURL:withPublishingHandler:, the system invokes your block for every relevant published and unpublished progress object. Sometimes you need to implement edge-triggered behavior, in which you do something either exactly when new progress begins or not at all.

In the example above, the Dock doesn’t animate file icons when this method returns YES.

There’s no reliable definition of before in this case, which involves multiple processes in a preemptively scheduled system. Don’t use this method for anything more important than best efforts at animating. It can be inaccurate due to processes coming and going from unpredictable user actions.

See Also 参照

Observing and Controlling File Progress by Other Processes ファイル進捗を他のプロセスによって監視および制御する