The Influence of @ property (atomic, retain) of objective-C on reference count

First lookCode:

 @ Interface  Viewcontroller () {nsobject * OBJ _;} @ property (retain) nsobject * OBJ; //  Note that the default value is @ property (atomic ,....  @ End  @ Implementation  Viewcontroller  @ Synthesize OBJ = OBJ _; -( ID  ) Init {  If (Self =[Super init]) {OBJ _ = [[OBJ alloc] init];}  Int N = [OBJ _ retaincount];  ID X = Self. OBJ;  Int N2 = [OBJ _ retaincount]; //  Is N2 not equal to n?      Return  Self ;} 

conclusion:
nonatomic is not added as the property modifier. By default, this property is atomic. for atomic property , the compiler locks getter generation , and autorelease after the variable retain . Therefore, each call to getter, retaincount will add one (because it is autorelease, it will be release at the end of this eventloop execution ).