uilabel set y position programmatically
self.view.addSubview(button)
button.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([ 
    button.topAnchor.constraint(equalTo: self.balanceLabel.bottomAnchor,constant:30),
    button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),
])
