MGLMapView does not show any object added to the view controller - ios

Question

I have properly set up an Viewcontroller containing an UIView with class "MGLMapView", what I am trying add an button to the Viewcontroller, but when I run the app the button does not show.
Same if I do an external Viewcontroller and overlay the MapViewController, it runs, but it does not show.
Why is that? have anybody had a similar problem? and how do I solve it?
Thanks in advance!

Answer 1

I don't know about the MGLMapView but it should adhere to same rules as any other UIView object.
This example is based on a MKMapView but it should be analog for MGMapView. Put this code in your VC and add setUpViews() to your viewDidLoad() method.
Note: this code should put the MKMapView at the bottom of the view stack and the map view should take up the entire view (except the top 64 pts--I assumed a UINavigationView might be in use--if not just change 64.0 to 0.0 in the constraints). Then it adds a UIButton on top of the MKMapView centered in the x direction with a width of 150 a height of 40 and 20 from the bottom of the view.
let map: MKMapView = {
let view = MKMapView()
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
let button: UIButton = {
let view = UIButton()
// Add or change attributes as you need
view.backgroundColor = UIColor.green
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
fileprivate func setUpViews(){
// Add the map first
self.view.addSubview(map)
// Add the button now it will be on top of the map view
self.view.addSubview(button)
map.delegate = self;
NSLayoutConstraint.activate([
map.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 64.0),
map.bottomAnchor.constraint(equalTo: self.view.bottomAnchor),
map.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
map.trailingAnchor.constraint(equalTo: self.view.trailingAnchor)
])
NSLayoutConstraint.activate([
button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor, constant: 0.0),
button.heightAnchor.constraint(equalToConstant: 40.0),
button.widthAnchor.constraint(equalToConstant: 150.0),
button.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: -20.0),
])
}