When SwiftUI was first launched, one of many nice options that piqued my curiosity was the moment preview operate. This characteristic empowers builders to preview the person 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 newest launch of Xcode, Apple expanded the utility of this characteristic to UIKit as effectively.
On this tutorial, let’s see how one can make use of this preview characteristic when creating 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 needs to be fairly acquainted. When you enter the preview code, Xcode exhibits an extra pane, offering a preview of your view controller.
As you alter 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(“Whats up”, for: .regular)
let motion = UIAction { motion in print(“Whats up”)
let alertController = UIAlertController(title: “Whats up”, message: “Whats up 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 “Whats up”. Like in SwiftUI growth, you may examine the person interface straight within the preview. When you press the “Whats up” button, a warning or alert will pop up.
Previewing View Controllers in Interface Builder
The #Preview macro can 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(identify: “Primary”, bundle: nil).instantiateViewController(withIdentifier: “LoginView”) as UIViewController
return vc } |
You employ the instantiateViewController methodology to instantiate the view controller and preview it in Xcode. Optionally, you may give 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 effectively. Builders can now preview the person 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 growth course of.
Founding father of AppCoda. Writer of a number of iOS programming books together with Starting iOS Programming with Swift and Mastering SwiftUI. iOS App Developer and Blogger. Observe me at Fb, Twitter and Google+.
