Visual Format Language width and height constraint not being respected

Question

I have this view controller set up on a storyboard, and I need to add a MapView to it programmatically.

I want the map to fill the view's width and have a constant height of 100 on both orientations. Also, I want a spacing of 10 to the imageView that's below the map.

This is the code I'm using.

_map = [MyClass sharedMap]; // Get singleton
[_map removeFromSuperview]; // Remove from the other VC view
[_map removeConstraints:[_map constraints]]; // Remove constraints if any
[[self view] addSubview:_map];
[[self view] addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|[_map]|" options:0 metrics:nil views:@{@"_map" : _map}]];
[[self view] addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_map(100)]-10-[_sellerImage]" options:0 metrics:nil views:@{@"_map" : _map, @"_imageView" : _imageView}]];

But the results are:

• the width is constant and not filling the screen width
• the height increases when it's on portrait orientation
• the 10 px spacing to the imageView is ok

Do I need to set a initial frame for the map?

This mapview is a singleton used in many views in order to save memory. This is its initialization code:

+ (MKMapView *)sharedMap {
  static MKMapView *mapView;
  static dispatch_once_t onceToken;

  dispatch_once(&onceToken, ^{
    mapView = [[MKMapView alloc] init];
    if (IS_IOS_7) {
      [mapView setShowsUserLocation:YES];
      [mapView setPitchEnabled:NO];
    }
    [mapView setAutoresizingMask:UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth];
  });

  return mapView;
}

Answer 1

I worked this out early this morning.
When I initialize the map view, I shouldn't be setting an Autoresize Mask. Instead I should set:
[mapView setTranslatesAutoresizingMaskIntoConstraints:NO];

It is necessary to set a frame for the map view just once. I opted to set it during its initialization. After that, constraints and VFL take control of its position and dimensions. All errors are gone and it works exactly as I wanted.

For the record, this is the full initialization method:

+ (MKMapView *)sharedMap {
  static dispatch_once_t onceToken;

  dispatch_once(&onceToken, ^{
    mapView = [[MKMapView alloc] init];
    [mapView setFrame:CGRectMake(0, 0, 1, 1)];

    // Configure the map view
    if (IS_IOS_7) {
      [mapView setShowsUserLocation:YES];
      [mapView setPitchEnabled:NO];
    }
    [mapView setTranslatesAutoresizingMaskIntoConstraints:NO];
  });

  return mapView;
}