When SwiftUI was first launched, one of many nice options that piqued my curiosity was the moment preview perform. This characteristic empowers builders to preview the consumer interface of any view inside Xcode, fully bypassing the necessity for a simulator.
Previous to Xcode 15, the preview characteristic was unique to the SwiftUI framework. Nonetheless, with the latest launch of Xcode, Apple expanded the utility of this characteristic to UIKit as nicely.
On this tutorial, let’s see how one can make use of this preview characteristic when growing UIKit apps.
Utilizing #Preview to Preview View Controllers
To preview a UIKit view or view controller in Xcode, all it’s worthwhile to do is about up a preview code block utilizing the #Preview macro. Right here is an instance:
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#Preview { let vc = ViewController() return vc } |
For many who have expertise utilizing the #Preview characteristic in SwiftUI, the syntax ought to be fairly acquainted. When you enter the preview code, Xcode reveals a further pane, offering a preview of your view controller.
As you modify the code of ViewController, Xcode ought to show the change immediately. For instance, you may attempt to modify the code like under:
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class ViewController: UIViewController {
lazy var helloButton: UIButton = { let button = UIButton(configuration: .borderedProminent())
button.setTitle(“Hiya”, for: .regular)
let motion = UIAction { motion in print(“Hiya”)
let alertController = UIAlertController(title: “Hiya”, message: “Hiya World”, preferredStyle: .alert) let alertAction = UIAlertAction(title: “Okay”, fashion: .default)
alertController.addAction(alertAction) self.current(alertController, animated: true) }
button.addAction(motion, for: .touchUpInside)
button.translatesAutoresizingMaskIntoConstraints = false
return button }()
override func viewDidLoad() { tremendous.viewDidLoad()
self.view.addSubview(helloButton)
helloButton.centerXAnchor.constraint(equalTo: view.centerXAnchor, fixed: 0).isActive = true helloButton.centerYAnchor.constraint(equalTo: view.centerYAnchor, fixed: 0).isActive = true
}
} |
The preview pane will present a button that claims “Hiya”. Like in SwiftUI improvement, you may test the consumer interface straight within the preview. In case you press the “Hiya” button, a warning or alert will pop up.
Previewing View Controllers in Interface Builder
The #Preview macro will also be used to preview view controllers designed in Interface Builder (or Storyboard). Assuming you’ve created a view controller, configured with a storyboard ID, you may write the next code to preview it in Xcode:
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#Preview(“LoginView”) { let vc = UIStoryboard(title: “Principal”, bundle: nil).instantiateViewController(withIdentifier: “LoginView”) as UIViewController
return vc } |
You utilize the instantiateViewController methodology to instantiate the view controller and preview it in Xcode. Optionally, you can provide the preview a reputation (e.g. LoginView).
Abstract
With the discharge of Xcode 15, Apple has expanded the moment preview characteristic, beforehand unique to SwiftUI, to UIKit as nicely. Builders can now preview the consumer interface of any UIKit view or view controller inside Xcode utilizing the #Preview macro, eliminating the necessity for a simulator. This characteristic additionally extends to view controllers designed in Interface Builder or Storyboard. Going ahead, profit from this preview characteristic to expedite your UIKit improvement course of.
Founding father of AppCoda. Creator of a number of iOS programming books together with Starting iOS Programming with Swift and Mastering SwiftUI. iOS App Developer and Blogger. Comply with me at Fb, Twitter and Google+.