Attempts to start the query.
- iOS 5.0+
- macOS 10.4+
- tvOS 9.0+
- watchOS 2.0+
YES when successful; otherwise,
A query may fail to start if it does not specify a
predicate, or if the query has already been started.
A query can’t be started if the receiver is already running a query or no predicate has been specified.
This method must be called from the receiver’s
operationQueue or on the main thread. For example:
A Boolean value that indicates whether the query has started. (read-only)
A Boolean value that indicates whether the receiver is in the initial gathering phase of the query. (read-only)
A Boolean value that indicates whether the query has stopped.
Stops the receiver’s current query from gathering any further results.