How much space should I leave out for a bottom Admob banner?

cocos2d-x C++
1

I left out about 100(don’t know the unit) in height at the bottom of the screen for the admob banner, which will be added at the end of the project.

For iphone 6, the height of the admob banner is about 100.

But, when I move to ipad, this height is different.

So some elements differ in position (in height direction).

For example:

float admobHeight = 100.0;

Vec2 desiredPosition = Vec2(0, 100);

auto sprite = Sprite::create("image.png");
sprite->setAnchorPoint(Vec2(0, 0));

// Leave out space for the bottom Admob banner.
sprite->setPosition(Vec2(desiredPosition.x, desiredPosition.y + admobHeight));

this->addChild(sprite);

I set DesignResolution as :

(AppDelegate.cpp)

static cocos2d::Size designResolutionSize = cocos2d::Size(768, 1136);

and Resolution policy NO_BORDER:

glview->setDesignResolutionSize(designResolutionSize.width, designResolutionSize.height, ResolutionPolicy::NO_BORDER);

How can I leave out just right amount of space in height at the bottom of my screen for Admob for every type of devices?