Bdtjtk

I have 2 views: aView and topView. Both of these have all the necessary constraints made in the interface builder.

Now I need to add a WKWebView instance to the view. So I've created a webPage property. Then I try to init the thing and add 4 constraints to it like so:

self.webPage = [[WKWebView alloc] init];



NSLayoutConstraint *topConstraint =[NSLayoutConstraint

                                   constraintWithItem: self.webPage

                                   attribute:NSLayoutAttributeTop

                                   relatedBy:NSLayoutRelationEqual

                                   toItem: self.topBar

                                   attribute:NSLayoutAttributeBottom

                                   multiplier:1.0

                                   constant:0.0];





NSLayoutConstraint *bottomConstraint =[NSLayoutConstraint

                                    constraintWithItem: self.webPage

                                    attribute:NSLayoutAttributeBottom

                                    relatedBy:NSLayoutRelationEqual

                                    toItem: self.aView

                                    attribute:NSLayoutAttributeBottom

                                    multiplier:1.0

                                    constant:50.0];





NSLayoutConstraint *leadingConstraint =[NSLayoutConstraint

                                    constraintWithItem: self.webPage

                                    attribute:NSLayoutAttributeLeading

                                    relatedBy:NSLayoutRelationEqual

                                    toItem: self.aView

                                    attribute:NSLayoutAttributeLeading

                                    multiplier:1.0

                                    constant:0.0];





NSLayoutConstraint *trailingConstraint =[NSLayoutConstraint

                                    constraintWithItem: self.webPage

                                    attribute:NSLayoutAttributeTrailing

                                    relatedBy:NSLayoutRelationEqual

                                    toItem: self.aView

                                    attribute:NSLayoutAttributeTrailing

                                    multiplier:1.0

                                    constant:0.0];



[self.aView addSubview: self.webPage];



[self.aView addConstraints: @[topConstraint, bottomConstraint, leadingConstraint, trailingConstraint]];

so that my WKWebView instance is always right under topView, 50 pt above aView.bottom and is stuck to the edges of the view.

But I get errors:

[LayoutConstraints] Unable to simultaneously satisfy constraints.

Probably at least one of the constraints in the following list is one you don't want. 

Try this: 

    (1) look at each constraint and try to figure out which you don't expect; 

    (2) find the code that added the unwanted constraint or constraints and fix it. 

and I can't understand what I did wrong.

You need to set translatesAutoresizingMaskIntoConstraints to false

self.webPage.translatesAutoresizingMaskIntoConstraints = false