programmatically update Autolayout Constraints which is set via Inspector

Question

I have a ViewController which has a tableview in it. I set its autolayout manually. Now I'm trying to change the autolayout constraints programmatically. How can I do that?

This is my code's screenshot

Thanks

Answer 1

You can change constraints programatically without any outlet:

for (_, value) in self.view.constraints.enumerate() {
        let constraint = value as NSLayoutConstraint

        if constraint == .Height {
            if value.firstItem.isEqual(self.tableView) {
                constraint.constant = 200.0
            }
        }
}

Answer 2

Follow these steps

1. Just select the constraint you want to update progrmatically eg. height
2. create an outlet of it. New referencing outlet.

3. eg. @IBOutlet weak var heightConstraint: NSLayoutConstraint!

4. update constant, heightConstraint.constant = 100.

Answer 3

为需要修改的约束设置出口并将其连接起来。