迅捷/重构

Question

I'm creating a view to use it as a subview within the viewDidLoad.

    override func viewDidLoad() {
    let backgroundView = UIView()
    backgroundView.translatesAutoresizingMaskIntoConstraints = false
    backgroundView.backgroundColor = UIColor.blackColor()

    let viewsDictionary = ["backgroundView":backgroundView]

    let backgroundView_constraint_H = NSLayoutConstraint.constraintsWithVisualFormat(
        "H:[backgroundView(10000)]",
        options: NSLayoutFormatOptions(rawValue: 0),
        metrics: nil, views: viewsDictionary)
    let backgroundView_constraint_V = NSLayoutConstraint.constraintsWithVisualFormat(
        "V:[backgroundView(10000)]",
        options: NSLayoutFormatOptions(rawValue:0),
        metrics: nil, views: viewsDictionary)

    backgroundView.addConstraints(backgroundView_constraint_H)
    backgroundView.addConstraints(backgroundView_constraint_V)

    backgroundView.alpha = 0.9

    self.tableView.backgroundView = backgroundView
}

What's the correct workaround to put all the code into an own .swift file and only call self.tableView.backgroundView = backgroundView at the viewDidLoad?

Help is very appreciated.

Answer 1

        class func backgroundView()->UIView {
            let backgroundView = UIView()
            backgroundView.translatesAutoresizingMaskIntoConstraints = false
            backgroundView.backgroundColor = UIColor.blackColor()
            backgroundView.frame = self.tableView.frame
            backgroundView.alpha = 0.9

self.tableView.backgroundView = backgroundView

Answer 2

You can extend UIView itself and write a class function that would return you this background view correctly configured. Save this in a file say UIView+extensions.swift

   extension UIView {

      class func backgroundView()->UIView {

        let backgroundView = UIView()
        backgroundView.translatesAutoresizingMaskIntoConstraints = false
        backgroundView.backgroundColor = UIColor.blackColor()

        let viewsDictionary = ["backgroundView":backgroundView]

        let backgroundView_constraint_H = NSLayoutConstraint.constraintsWithVisualFormat(
                                                                                         "H:[backgroundView(10000)]",
                                                                                         options: NSLayoutFormatOptions(rawValue: 0),
                                                                                         metrics: nil, views: viewsDictionary)
        let backgroundView_constraint_V = NSLayoutConstraint.constraintsWithVisualFormat(
                                                                                         "V:[backgroundView(10000)]",
                                                                                         options: NSLayoutFormatOptions(rawValue:0),
                                                                                         metrics: nil, views: viewsDictionary)

        backgroundView.addConstraints(backgroundView_constraint_H)
        backgroundView.addConstraints(backgroundView_constraint_V)

        backgroundView.alpha = 0.9

        return backgroundView

      }

    }

You can now access this as:

self.tableView.backgroundView = UIView.backgroundView()