When creating a new **Swift Playground** / .playgroundbook intended to be used on the **iPad App**, I often received the error message: 

*"Problem running playground. There was a problem encountered while running this playground. Check your code for mistakes."*

I could track this issue down to be caused when adding certain subviews to my live view. To be more precise, my goal is to split a UIImage into multiple parts and create new UIImageViews for them:

```
for x in 0..<parts {
    for y in 0..<parts {
        //Create UIImageView with cropped image
        let pieceView = UIImageView.init(frame: CGRect.init(x: CGFloat(x)*singleSize.width, y:CGFloat(y)*singleSize.height, width: singleSize.width, height: singleSize.height))
        let imageRef = image.cgImage!.cropping(to: CGRect.init(x:0, y:0, width: 100, height: 100));
        pieceView.image = UIImage.init(cgImage: imageRef!)
        //Add them to an array
        self.viewArray.append(pieceView)
    }
}

```

And that's where things become very tricky for me: **Adding 7 of these UIImageViews now works without a problem. But as soon as I want to add 8 or more of them, the playground stops working** and gives the error message "Problem running playground..." (see above)

What I tested so far:

* Adding UIImageViews with the same image does not cause this problem
* Cropping the UIImage in a background thread and adding the view on the main thread does not help either
* Creating the UIImageViews without adding them to the live-view does not cause any problems
* The code works well when being executed on a mac playground, no matter how man views to add