Sets the current thread’s priority.
- iOS 2.0+
- macOS 10.2+
- tvOS 9.0+
- watchOS 2.0+
The new priority, specified with a floating point number from 0.0 to 1.0, where 1.0 is highest priority.
YES if the priority assignment succeeded,
The priorities in this range are mapped to the operating system's priority values.