OC内存管理

//
//  main.m


#import <Foundation/Foundation.h>
@interface Animal : NSObject 
-(void)showMsg;
@end

@implementation Animal
-(void)showMsg{
    NSLog(@"我是哈哈");
}
-(void)dealloc{   //当减到0的时候执行
    NSLog(@"释放了");
    [super dealloc];
}

@end
int main(int argc, const char * argv[]) {
    @autoreleasepool {
   
        Animal *a = [[Animal alloc]init];//alloc+1
        NSUInteger count = [a retainCount];
        NSLog(@"%lu",count);
        
        [a retain];                     //+1
        NSUInteger count1 = [a retainCount];
        NSLog(@"%lu",count1);
        
        [a release];                    //-1
        NSUInteger count2 = [a retainCount];
        NSLog(@"%lu",count2);
     
        [a release];                    //-1
        NSUInteger count3 = [a retainCount];
        NSLog(@"%lu",count3);
  
    }
    return 0;
}