RTSpinView as iBoutlet with contraint not working

[cuddle-sujeet]

I tried creating a spinner view in the view controller via xib using IBOutlet and in its didSet set up its style.
@IBOutlet weak var testSpinner:RTSpinKitView! {
didSet {
testSpinner.style = .styleThreeBounce
testSpinner.color = .red
testSpinner.startAnimating()
}
}

but I am not able to see the spinner on the view.
I intend to start/stop the spinner after some service response.
Note:- the constraints are not failing.

Am I messing-up the spinner layer by using constraint? because When I give frame to spinner using CGrectMake() I am able to see the spinner.