Put a view at the end of UIScrollview - Swift - ios

Question

My aim is to set a UIView at the end (right bottom) of a UIScrollView. I saw solution using UIContentSize but I don't want to use this property because it is not adapted : The UIView width isn't equal to the UIScrollview contentSize.
The UIView is a subview of the UIScrollView and I only need to scroll horizontally. I think I must use constraints in order to stick my UIView at the end of the UIscrollview (that means the UIView Right side is the same that the UIScrollView right side, both have the same height)
What I did is :
let horizontalConstraint = NSLayoutConstraint(item: self.myView , attribute: NSLayoutAttribute.Right, relatedBy: NSLayoutRelation.Equal, toItem: self.myScrollView , attribute: NSLayoutAttribute.Right, multiplier: 1, constant: 0)
self.myScrollView.addConstraint(horizontalConstraint)
let verticalConstraint = NSLayoutConstraint(item: self.myView, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: self.myScrollView, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0)
self.myScrollView.addConstraint(verticalConstraint)
I'm a bit confused and stuck about how to set this constraints, I'm probably wrong because my view doesn't display anymore. Do I need to define all the constraint or only the one for the right and one for the top ? Any advice ? Thanks
EDIT :
The solution I want could be represented like this :

Answer 1

UIScrollView takes it's content size from it's subviews, so it will only be as large as what it contains. We can't set it's size independently. Everything should be in a subview.
Decide on the size of myScrollView you want:
let myViewWidth = myView.frame.width
let myViewHeight = myView.frame.height
let screenWidth = myScrollView.frame.width
let scrollContentWidth = myViewWidth + screenWidth
Create a subview, let's call it widthView
let widthView = UIView(frame: CGFloat(x: 0, y: 0, width: scrollContentWidth, height: myViewHeight))
myScrollView.addSubview(widthView)
let leadingEdgeConstraint = NSLayoutConstraint(item: widthView, attribute: NSLayoutAttribute.Leading, relatedBy: NSLayoutRelation.Equal, toItem: myScrollView, attribute: NSLayoutAttribute.Leading, multiplier: 1, constant: 0)
myScrollView.addConstraint(leadingEdgeConstraint)
let trailingEdgeConstraint = NSLayoutConstraint(item: widthView, attribute: NSLayoutAttribute.Trailing, relatedBy: NSLayoutRelation.Equal, toItem: myScrollView, attribute: NSLayoutAttribute.Trailing, multiplier: 1, constant: 0)
myScrollView.addConstraint(trailingEdgeConstraint)
let widthContainerConstraint = NSLayoutConstraint(item: widthView, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: scrollContentWidth)
myScrollView.addConstraint(widthContainerConstraint)
Now add your myView to that view:
widthView.addSubview(myView)
myView.translatesAutoresizingMaskIntoConstraints = false
let horizontalConstraint = NSLayoutConstraint(item: myView , attribute: NSLayoutAttribute.Right, relatedBy: NSLayoutRelation.Equal, toItem: widthView , attribute: NSLayoutAttribute.Right, multiplier: 1, constant: 0)
widthView.addConstraint(horizontalConstraint)
let heightConstraint = NSLayoutConstraint(item: myView, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: myViewHeight)
widthView.addConstraint(heightConstraint)
let widthConstraint = NSLayoutConstraint(item: myView, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: myViewWidth)
widthView.addConstraint(widthConstraint)

Answer 2

Thanks to informations provided by #Tim I finally managed this without using another Subview :
Solution :
// Create a view
myView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: self.myScrollView.frame.height))
myView.backgroundColor = UIColor.redColor()
self.myScrollView.addSubview(myView)
// constraints
myView.translatesAutoresizingMaskIntoConstraints = false
let trailingSpaceConstraint = NSLayoutConstraint(item: self.myScrollView, attribute: NSLayoutAttribute.Trailing, relatedBy: NSLayoutRelation.Equal, toItem: myView, attribute: NSLayoutAttribute.Trailing, multiplier: 1, constant: 0)
myScrollView.addConstraint(trailingSpaceConstraint)
let screenWidth = self.view.frame.width
let leadingSpaceConstraint = NSLayoutConstraint(item: self.myView, attribute: NSLayoutAttribute.Leading, relatedBy: NSLayoutRelation.Equal, toItem: self.myScrollView, attribute: NSLayoutAttribute.Leading, multiplier: 1, constant: screenWidth - 15)
myScrollView.addConstraint(leadingSpaceConstraint)
let widthConstraint = NSLayoutConstraint(item: self.myView, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.Width, multiplier: 1, constant: 100)
myScrollView.addConstraint(widthConstraint)
let bottomConstraint = NSLayoutConstraint(item: self.myScrollView, attribute: NSLayoutAttribute.Bottom, relatedBy: NSLayoutRelation.Equal, toItem: self.myView, attribute: NSLayoutAttribute.Bottom, multiplier: 1, constant: 0)
myScrollView.addConstraint(bottomConstraint)
let topConstraint = NSLayoutConstraint(item: self.myView, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: self.myScrollView, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0)
myScrollView.addConstraint(topConstraint)
let heightConstraint = NSLayoutConstraint(item: self.myView, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: self.myScrollView, attribute: NSLayoutAttribute.Height, multiplier: 1, constant: 0)
myScrollView.addConstraint(heightConstraint)