Add UIView to UIWindow causes memory leak - ios

Question

I have a view like this:
#interface MyView ()
#property (nonatomic, strong) UIView* subView;
#end
#implementation MyView
#pragma mark - init && dealloc
-(instancetype)init
{
self = [super init];
if (self){
[self setupSubView];
[self setupAutoLayoutSubView];
}
return self;
}
#pragma mark - setup
-(void)setupSubView
{
_subView = [UIView newAutoLayoutView];
[self addSubview:_subView];
}
-(void)setupAutoLayoutSubView
{
// autolayout: to centralize the subView
// if you don't use PureLayout, you can use the traditional way
[_subView autoCenterInSuperview];
}
#end
When I add this view into Window, the reference counting on this view will be increased to 3.
MyView* v = [[MyView alloc] init];
NSLog(#"reference counting = %ld",CFGetRetainCount((CFTypeRef)v)); //- 1
UIWindow* window = [[UIApplication sharedApplication] keyWindow];
[window addSubView:v];
NSLog(#"reference counting = %ld",CFGetRetainCount((CFTypeRef)v)); //- 3 INCORRECT
The strange thing is if I comment the "autolayout" part from method: "setupAutoLayoutSubView", the reference counting is correct ( = 2 )
or if I add my view to a normal view, the reference counting is correct as well
MyView* v = [[MyView alloc] init];
NSLog(#"reference counting = %ld",CFGetRetainCount((CFTypeRef)v)); //- 1
UIView* normalView = [[UIView alloc] init];
[normalView addSubView:v];
NSLog(#"reference counting = %ld",CFGetRetainCount((CFTypeRef)v)); //- 2 : CORRECT