MarkupKit 4.1 Released

MarkupKit 4.1 is now available for download. This release adds support for live preview of markup documents within Xcode:

View classes tagged with IB_DESIGNABLE or @IBDesignable can now call the new preview:owner: method MarkupKit adds to the UIView class to validate markup changes at design time, avoiding the need to launch the iOS simulator. If an error occurs while loading the document, a label containing the error message will be overlaid on top of the view instance, allowing typos and other errors to be quickly identified.

For example, the following class provides a preview of the DetailViewController.xml document in the MarkupKit sample application. The view’s implementation of the prepareForInterfaceBuilder() method provides placeholder content; a temporary controller instance is used to ensure that outlets, actions, and bindings are handled properly:

class DetailViewControllerPreview: LMRootView {
    override func prepareForInterfaceBuilder() {
        let owner = DetailViewController(nibName: nil, bundle: nil)

        preview("DetailViewController", owner: owner)

        owner.iconImageView.image = UIImage(named: "BeachIcon", in: Bundle(for: type(of: self)), compatibleWith: nil)

        owner.headingLabel.text = "Heading Text"
        owner.detailLabel.text = "Detail Message"

Note that this class is only used at design time – the view controller is still responsible for loading the view document at run time:

override func loadView() {
    view = LMViewBuilder.view(withName: "DetailViewController", owner: self, root: LMRootView())

Live preview can significantly reduce development time, since it eliminates the round trip through the simulator that is typically required to test an update. Using live preview, successive updates can be quickly verified, and the simulator launched only when the desired layout has been achieved.

For more information, see the project README.