Is it possible to preview animation done for UIView with animateWithDuration in Playground? I am adding XCPShowView right after initialization of UIView and its shows everything
Yes, it is (checked on Xcode 6.1.1, but may apply to earlier versions).
You should:
Select the "Run in Full Simulator" option (see this answer for a step-by-step).
Add the view you wish to animate within a container view.
For example, this shows a black square moving in a down-left motion:
import UIKit
import XCPlayground
let container = UIView(frame: CGRect(x: 0.0, y: 0.0, width: 100.0, height: 100.0))
XCPShowView("container", container)
let view = UIView(frame: CGRect(x: 0.0, y: 0.0, width: 50.0, height: 50.0))
view.backgroundColor = UIColor.blackColor()
container.addSubview(view)
UIView.animateWithDuration(5.0, animations: { () -> Void in
view.center = CGPoint(x: 75.0, y: 75.0)
})