oc-Memory management mechanism

1. Memory management mechanism

• Referred to as "reference count" (retain counting)
• Each object has a reference count (retain count)

2. Why to manage memory

In our iOS development process, the program memory more than 20M will receive a memory warning, to 30M when the program will be a flash, this may be a lot of developers crash place.

The 3.iOS memory mechanism is mainly divided into ARC and MRC

• ARC automatically manages memory
• MRC Manual Memory Management

4. Principles of Memory management

• The essence of memory management is the management of memory reference count
• There are +1 must have corresponding-1
• Only when you see alloc,retain,copy, you need to releas in the current method or in the interior;
• When a pointer is retain,alloc,copy, it needs to be release within the current method or class.
• An object created by the convenience constructor, which has been identified within the method once Autorelease
• Container memory Management: An object is placed in the container, the reference count of this object +1, when the object is removed from the container, the object reference count will be-1.

5. How the system reclaims memory Dealloc

Never call this method

In the MRC, when you rewrite this method, you need to write a [super Dealloc] in the last line;

oc-Memory management mechanism