将视图控制器添加到具有约束的uiview中

Question

In a storyboard, I have a 3 screens (controller view): 1) Controller "main" containing a uiview named cntdetail and a button named viewswitch 2) Controller "A" with several elements (label, textfields...) 3) Controller "B" with also several elements

What I need it to load the view A in cntdetail when the view appears and switch from A to B when tapping the button and vice versa.

What I'm doing (it is in C# but nearly like swift):

In the Main ViewDidLoad:

cviewA = Storyboard.InstantiateViewController("SaisieVocale");
cviewB = Storyboard.InstantiateViewController("SaisieDetaillee");
AddChildViewController(cviewA);
AddChildViewController(cviewB);
viewAcontenth = GetContentHeight(cviewA.View); //a personal function that calculate the height of the content, it works
viewBcontenth = GetContentHeight(cviewB.View);

when clicking the button (and nearly the same in viewdidappear) (I use A to simplify but it is once A once B):

cviewB.View.RemoveFromSuperview();

//change the height constraint of the uiview to fit the height of my views 
        foreach (var cst in cntdetails.Constraints)
        {
            if ((UIView)cst.FirstItem == cntdetails || (UIView)cst.SecondItem == cntdetails)
            {
                if (cst.FirstAttribute == NSLayoutAttribute.Height)                               //il faut modifier la contrainte de hauteur
                    cst.Constant = viewAcontenth;
            }
        }
cntdetails.AddSubview(cviewA.View);

But it doesn't work as expected, the hiehgt of the main view is increased a bit each time I click the button and one of the view (A or B) in not visible.

EDIT: cntdetails has equal constraint at top, leading, trailing and height with the main view. Then I just have to modify the height constraint and actualy this part work.

EDIT: I tried to add constrains to keep the size of A and B following the size of cntdetail but it's not better:

cviewA.View.TranslatesAutoresizingMaskIntoConstraints = false;
cviewA.View.LeadingAnchor.ConstraintEqualTo(cntdetails.LeadingAnchor).Active = true;
cviewA.View.TrailingAnchor.ConstraintEqualTo(cntdetails.TrailingAnchor).Active = true;
cviewA.View.WidthAnchor.ConstraintEqualTo(cntdetails.WidthAnchor).Active = true;
cviewA.View.HeightAnchor.ConstraintEqualTo(cntdetails.HeightAnchor).Active = true;

Answer 1

Finally I found some mistakes I made. This page helped For the main view that increased it was because of my function calculating the view height.

First in the viewdidload:

cviewA = Storyboard.InstantiateViewController("SaisieVocale");
cviewB = Storyboard.InstantiateViewController("SaisieDetaillee");
//AddChildViewController(cviewA);   no need to do that here
//AddChildViewController(cviewB);
viewAcontenth = GetContentHeight(cviewA.View); //a personal function that calculate the height of the content, it works
viewBcontenth = GetContentHeight(cviewB.View);

When switching from A to B :

//change the height constraint of the uiview to fit the height of my views 
        foreach (var cst in cntdetails.Constraints)
        {
            if ((UIView)cst.FirstItem == cntdetails || (UIView)cst.SecondItem == cntdetails)
            {
                if (cst.FirstAttribute == NSLayoutAttribute.Height)                               //il faut modifier la contrainte de hauteur
                    cst.Constant = viewAcontenth;
            }
        }

//first remove B except the first time
cviewB.DidMoveToParentViewController(null);
cviewB.View.RemoveFromSuperview();
cviewB.RemoveFromParentViewController();

//next add A:
this.AddChildViewController(cviewA);
cviewA.View.Frame= cntdetails.Bounds;
cntdetails.AddSubview(cviewA.View);
cviewA.DidMoveToParentViewController(this);