.h文件

@interface myclass:NSObject

@property(nonatomic,retain)NSArray*MyArray;

@end

.m文件

@implementation myclass

-(void)viewDidLoad

{

  [superviewDidLoad];

  _MyArray=[[NSArrayalloc]initWithObjects:@"",nil];

  NSLog(@"%lu",(unsignedlong)[self.MyArray retainCount]);//输出1

  self.MyArray=[[NSArrayalloc]initWithObjects:@"",nil];

  NSLog(@"%lu",(unsignedlong)[self.MyArray retainCount]);//输出2

  我的理解是

  self.MyArray=[[NSArrayalloc]initWithObjects:@"",nil];

  相当于

  NSArray*a=[[NSArrayalloc]initWithObjects:@"",nil];

  self. MyArray =a;

  而self.MyArray会调用myArray的set方法，

    -(void)setMyArray:( NSArray *)Array

   {

      if(Array!= MyArray)

     {

        [MyArray release];

        MyArray =[Array retain];

     }

  }

}