Program Subview's Vertical Spacing to Bottom Constraint - ios

Question

SecondViewController adds a UIView that contains a MKMapView as a subview inside an IBAction method:
if(_tagTwo == 4){
seg2_buttonImg = #"Maps.png";
UIImage *btnImage1 = [UIImage imageNamed:seg2_buttonImg];
[_left_button setImage:btnImage1 forState:UIControlStateNormal];
[_table removeFromSuperview];
[mapVC layoutMapView];
[self.view addSubview:mapVC.view];
return;
}
mapVC is created in ViewDidLoad with mapVC = [[CollectionMapViewController alloc] init];
Edit: new code for adding constraints, taken from #Reinier Melian:
#implementation CollectionMapViewController
#synthesize mapView;
- (void)viewDidLoad
{
if (floor(NSFoundationVersionNumber) > NSFoundationVersionNumber_iOS_6_1) {
//[segmentedControl setBackgroundColor:[UIColor whiteColor]];
//[segmentedControl setBackgroundColor:[UIColor leafletBrown]];
[segmentedControl setBackgroundColor:[UIColor leafletLightBrown]];
segmentedControl.layer.cornerRadius = 5;
}
self.mapView.translatesAutoresizingMaskIntoConstraints = NO;
NSArray * verticalConstraints = [NSLayoutConstraint constraintsWithVisualFormat:#"V:|[mapView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(self.mapView)];
NSArray * horizontalConstraints = [NSLayoutConstraint constraintsWithVisualFormat:#"H:|[mapView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(self.mapView)];
//Add constraints to the Parent
[self.view addConstraints:verticalConstraints];
[self.view addConstraints:horizontalConstraints];
}
CollectionMapViewController.h:
#interface SecondViewController : UIViewController <NSFetchedResultsControllerDelegate, CollectionMapViewControllerDelegate>{
CollectionMapViewController* mapVC;
}
#property (nonatomic, retain) CollectionMapViewController* mapVC;
The problem is that it adds the MKMapView to the top of the screen:
I tried to constrain the MKMapView to the bottom of the screen by adding following code to viewDidLoad of MapViewController
mapView.translatesAutoresizingMaskIntoConstraints = NO;
NSLayoutConstraint *bottom =[NSLayoutConstraint
constraintWithItem:mapView
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1.0f
constant:0.f];
//Add constraints to the Parent
[self.view addConstraint:bottom];
But it just makes the map go black (or more likely moves it completely off the screen?).
What I am trying to get is this:
I would appreciate any help! Thank you so much!

Answer 1

When you add mapView.translatesAutoresizingMaskIntoConstraints = NO; your map rect size is equal to zero if there are not enough constraints to define the correct frame, that is why you have your screen black, you need define all the constraints needed by your MKMapView
Updated using dynamic height constraints
try with this code
self.mapView.translatesAutoresizingMaskIntoConstraints = NO;
CGFloat mapHeigthValue = self.view.frame.size.height/3; //setting the mapView heigth = 1/3 of view height this is an example
NSArray * verticalConstraints = [NSLayoutConstraint constraintsWithVisualFormat:[NSString stringWithFormat:#"V:[mapView(%f)]|",mapHeigthValue] options:0 metrics:nil views:#{#"mapView":self.mapView}];
NSArray * horizontalConstraints = [NSLayoutConstraint constraintsWithVisualFormat:#"H:|[mapView]|" options:0 metrics:nil views:#{#"mapView":self.mapView}];
//Add constraints to the Parent
[self.view addConstraints:verticalConstraints];
[self.view addConstraints:horizontalConstraints];

Answer 2

In viewDidLoad:
mapView.translatesAutoresizingMaskIntoConstraints = NO;
/*Set width and height of mapview */
NSLayoutConstraint *widthConst = [NSLayoutConstraint constraintWithItem:mapView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:400];
NSLayoutConstraint *heightConst = [NSLayoutConstraint constraintWithItem:mapView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:300];
[self.view addConstraint:widthConst];
[self.view addConstraint:heightConst];
/*creater X and Y constraints for mapview */
NSLayoutConstraint *centreHorizontallyConstraint = [NSLayoutConstraint
constraintWithItem:mapView
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterX
multiplier:1.0
constant:0];
[self.view addConstraint:centreHorizontallyConstraint];
NSLayoutConstraint *bottomConstraint = [NSLayoutConstraint
constraintWithItem:mapView
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:140];
[self.view addConstraint:bottomConstraint];