@ PROPERTY PARAMETER

@ Property is an attribute access statement. The extension number supports the following attributes:
1,Getter = gettername, setter = settername, Set the method names of setter and getter
2,Readwrite, Readonly, set the available access level
2,AssignThe setter method directly assigns values without any retain operations. To solve the problem of the original type and cycle reference
3,Retain, The setter method performs the release old value on the parameter and retain the new value. All implementations are in this Order (CC has relevant information)
4,CopyThe setter method performs the copy operation. Like the retain processing process, the old value is release first, and then the new object is copied. retaincount is 1. This is a mechanism introduced to reduce context dependencies.
5,NonatomicNon-atomic access without synchronization. multi-thread concurrent access improves performance. Note: If this attribute is not added, both access methods are atomic transaction access by default. The lock is added to the object instance level.