object-c-memory Management Object life cycle

The Autoreleasepool pool is destroyed when the object labeled Autorelease is called once release

Person *p2=[[[person Alloc]init]autorelease]; Mark as Autorelease

Assign default parameters, setter methods do not cause a change in reference count

The Retain:setter method first frees the old object, assigns the value of the old object to the input object, and kills the reference count of the input object to 1

The copy setter method first resumes an identical object, and the new object reference counter is 1 old object reference count unchanged.

Nonatomic default parameter non-atomic access, no synchronization, multi-threaded concurrent access improves performance, and if this attribute is not added, the default is two access methods are atomic transaction access. The lock is added to the owning object instance level.

Atomic default parameters, atomic access

ARC Memory Management Machine

object-c-memory Management Object life cycle