Properties of memory management and @property

Properties of memory management and @property

Directory

• Understanding of memory management
• Management of Memory

Ownership and memory management principles for objects

Rationally solve the problems caused by memory management

Auto Free Pool

• Properties of the @property

Understanding of memory management

Management of Memory

Ownership and memory management principles for objects

Both an object and a function can have administrative rights on the class object, so objects and functions need to be responsible for creating and releasing class objects

A reasonable solution to the problems caused by memory management (in the MRC, there is a release of the owning object on the Dealloc)

Stage One

MyClass *myclass = [[MyClass alloc] init];

MyClass's behavior

[MyClass release];

Phase II

-(void) Setengine: (engine *) newengine{engine = Newengine;}

Car *car = [[Car alloc] init];

Engine *engine = [[Engine alloc] init]; 1

[Car setengine:engine]; 1

[Engine release]; 0 causes the engine in the car object to point to an empty object

Stage Three

Adjustment to Setter:-(void) Setengine: (engine *) newengine{engine = [newengine retain];};

A problem exists:

Engine *engine1 = [engine new]; 1

[Car setengine:engine1]; 2

[Engine1 release]; 1

Engine *engine2 = [engine new]; 1

[Car setengine:engine2]; 1

[Car release]; 1 The Engine1 is not released at this time, that is, the object that the car originally pointed to was not released

Stage Three

Continue adjustment to setter:-(void) Setengine: (engine *) newengine{[engine release]; engine = [newengine retain]; }

There is a problem

Engine *engine = [engine new]; 1

Car *car1 = [car new];

Car *car2 = [car new];

[Car1 Setengine:engine]; 2

[Engine release]; 1

[Car2 SETENGINE:[CAR1 engine]]; Error at this point the engine's reference count is 0,CAR1 and CAR2 cannot use its Engine property

Stage Four

Continue adjustment to setter:-(void) Setengine: (Engine *) newengine{[newengine retain]; [Engine release];　　engine = Newengine; }

Auto Free Pool

Properties of the @property

Properties for memory management and @property