问在objective-c中解除锁分配的正确方法是什么？

EN

-(id)initWithImageFileName:(NSString*)imageFileName
{
    if (self = [super init])
    {
        _imageFileName = [imageFileName retain];
        _loadBackgroundCalled = NO;
        _deallocing = NO;
        _lockObject = [[NSObject alloc]init];
    }

    return self;
}

-(void)dealloc
{
    _deallocing = YES;

    @synchronized(_lockObject)
    {
        ..... <releases some stuff>

    }

    [_lockObject release];
    _lockObject = nil;


    [_imageFileName release];
    _imageFileName = nil;

    [super dealloc];
}

-(void)loadBackground
{
    @synchronized(_lockObject)
    {
        if (!_deallocing)
        {
            if (!_loadBackgroundCalled) 
            {
                _loadBackgroundCalled = YES;
                ....
            } 
        }
    }
}

-(void)loadSprite:(XYTexture*)texture
{
    @synchronized(_lockObject)
    {
        ....
    }
}

-(void)unloadBackground
{
    @synchronized(_lockObject)
    {
        if (!_deallocing)
        {
            .....
            _loadBackgroundCalled = NO;
        }
    }
}