CODEWITHSUNDEEP
iosswiftuitableviewsubview
Jeremy
Jeremy

Reputation: 145

Positioning a subview when called from an UITableviewControllers in Swift

I have used in my UITableviewController:

self.view.superview?.addSubview(PopUpControls)

It pops-up fine but not in the right position. How do you set the position for a subview?

Upvotes: 0

Views: 3210

Answers (2)

Caleb Kleveter
Caleb Kleveter

Reputation: 11494

You probably just need to change the origin after you add the view as a sub-view:

// Set the Y (up, down) position of the view.
PopUpControls.frame.origin.y = <CGFLOAT>
// Set the X (left, right) position of the view
PopUpControls.frame.origin.x = <CGFLOAT>

Edit:

To add constraints to a view, you do it like this:

// 1
if let superView = self.view.superview {

    // 2
    superView.addSubview(PopUpControls)

    // 3
    PopUpControls.translatesAutoresizingMaskIntoConstraints = false

    // 4
    NSLayoutConstraint.activate([

            // 5
            NSLayoutConstraint(item: PopUpControls, attribute: .top, relatedBy: .equal, toItem: superView, attribute: .top, multiplier: 1.0, constant: 15),

            // 6
            NSLayoutConstraint(item: PopUpControls, attribute: .left, relatedBy: .equal, toItem: superView, attribute: .left, multiplier: 1.0, constant: 5),

            // 7
            PopUpControls.heightAnchor.constraint(equalToConstant: 15),

            //8
            PopUpControls.widthAnchor.constraint(equalToConstant: 10)
        ])
}

Here is what I am doing:

  1. Making sure the controller's view has a super view (Question specific.).
  2. Adding the view to the super view.
  3. Setting the view so we don't have any auto-generated constraints. This could cause problems.
  4. Activating any constraints in the array passed into the method.
  5. Creating a constraint between the view (PopUpControls) and the super view. It is connected to the top of each of the elements with a distance of 15 points.
  6. Doing the same as #5, just the left of each element instead of the top.
  7. Setting the elements height to 15 points.
  8. Setting the elements width to 10 points.

This should be done in the viewDidLayoutSubviews method of the controller.

Upvotes: 3

Tiddly
Tiddly

Reputation: 1620

self.view.superview?.addSubview

Something has gone wrong if you ever need to do this.

The common way to send messages back up the chain is to use delegation.

https://developer.apple.com/library/content/documentation/General/Conceptual/DevPedia-CocoaCore/Delegation.html

Basically you define a protocol that one object has a reference to and the other object implements. That way you can send messages from the first object to the second. A child view should never be directly responsible for adding views directly to it's superview.

For the actual problem you have with setting the position, it depends on if you are using autolayout or not. If you are not them you simply need to set the x and y components of the view PopUpControls frame. If you are using autolayout then you will need to define it's constraints.

Upvotes: 0

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