Width and Height Equal to its superView using autolayout programmatically?

Question

I've been looking for a lot of snippets in the net and I still can't find the answer to my problem. My question is I have a scrollView(SV) and I want to add a button inside scrollView(SV) programmatically with same width and height of its superview which is scrollView(SV) so that when user rotate the device button will have the same frame of scrollView(SV). how to do the NSLayout/NSLayoutConstraint? thanks

Answer 1

If someone is looking for a Swift solution – I would create a Swift extension for UIView which will help you each time you want to bind a subviews frame to its superviews bounds:

Swift 2:

extension UIView {      /// Adds constraints to this `UIView` instances `superview` object to make sure this always has the same size as the superview.     /// Please note that this has no effect if its `superview` is `nil` – add this `UIView` instance as a subview before calling this.     func bindFrameToSuperviewBounds() {         guard let superview = self.superview else {             print("Error! `superview` was nil – call `addSubview(view: UIView)` before calling `bindFrameToSuperviewBounds()` to fix this.")             return         }          self.translatesAutoresizingMaskIntoConstraints = false         superview.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[subview]-0-|", options: .DirectionLeadingToTrailing, metrics: nil, views: ["subview": self]))         superview.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-0-[subview]-0-|", options: .DirectionLeadingToTrailing, metrics: nil, views: ["subview": self]))     }  } 

Swift 3:

extension UIView {      /// Adds constraints to this `UIView` instances `superview` object to make sure this always has the same size as the superview.     /// Please note that this has no effect if its `superview` is `nil` – add this `UIView` instance as a subview before calling this.     func bindFrameToSuperviewBounds() {         guard let superview = self.superview else {             print("Error! `superview` was nil – call `addSubview(view: UIView)` before calling `bindFrameToSuperviewBounds()` to fix this.")             return         }          self.translatesAutoresizingMaskIntoConstraints = false         superview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-0-[subview]-0-|", options: .directionLeadingToTrailing, metrics: nil, views: ["subview": self]))         superview.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-0-[subview]-0-|", options: .directionLeadingToTrailing, metrics: nil, views: ["subview": self]))     } } 

Swift 4.2:

extension UIView {      /// Adds constraints to this `UIView` instances `superview` object to make sure this always has the same size as the superview.     /// Please note that this has no effect if its `superview` is `nil` – add this `UIView` instance as a subview before calling this.     func bindFrameToSuperviewBounds() {         guard let superview = self.superview else {             print("Error! `superview` was nil – call `addSubview(view: UIView)` before calling `bindFrameToSuperviewBounds()` to fix this.")             return         }          self.translatesAutoresizingMaskIntoConstraints = false         self.topAnchor.constraint(equalTo: superview.topAnchor, constant: 0).isActive = true         self.bottomAnchor.constraint(equalTo: superview.bottomAnchor, constant: 0).isActive = true         self.leadingAnchor.constraint(equalTo: superview.leadingAnchor, constant: 0).isActive = true         self.trailingAnchor.constraint(equalTo: superview.trailingAnchor, constant: 0).isActive = true      } } 

Then simply call it like this:

// after adding as a subview, e.g. `view.addSubview(subview)` subview.bindFrameToSuperviewBounds() 

Answer 2

I'm not sure if this is the most efficient way to do it, but it works..

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom]; button.translatesAutoresizingMaskIntoConstraints = NO; // initialize   [coverForScrolView addSubview:button];  NSLayoutConstraint *width =[NSLayoutConstraint                                     constraintWithItem:button                                     attribute:NSLayoutAttributeWidth                                     relatedBy:0                                     toItem:coverForScrolView                                     attribute:NSLayoutAttributeWidth                                     multiplier:1.0                                     constant:0]; NSLayoutConstraint *height =[NSLayoutConstraint                                      constraintWithItem:button                                      attribute:NSLayoutAttributeHeight                                      relatedBy:0                                      toItem:coverForScrolView                                      attribute:NSLayoutAttributeHeight                                      multiplier:1.0                                      constant:0]; NSLayoutConstraint *top = [NSLayoutConstraint                                    constraintWithItem:button                                    attribute:NSLayoutAttributeTop                                    relatedBy:NSLayoutRelationEqual                                    toItem:coverForScrolView                                    attribute:NSLayoutAttributeTop                                    multiplier:1.0f                                    constant:0.f]; NSLayoutConstraint *leading = [NSLayoutConstraint                                        constraintWithItem:button                                        attribute:NSLayoutAttributeLeading                                        relatedBy:NSLayoutRelationEqual                                        toItem:coverForScrolView                                        attribute:NSLayoutAttributeLeading                                        multiplier:1.0f                                        constant:0.f]; [coverForScrolView addConstraint:width]; [coverForScrolView addConstraint:height]; [coverForScrolView addConstraint:top]; [coverForScrolView addConstraint:leading];