Let’s kick off with a universally acknowledged truth of iOS development: sometimes, we must halt a view controller dismissal. It could be because of a late data arrival, a user decision, or any number of reasons. Whichever the case may be, delaying dismissal of a view controller in Swift can be an essential skill.
In this article, we will walk you through the process in a step-by-step manner, highlighting the key concepts under the hood and the Swift libraries involved in this simple yet intricate mechanism.
Swift: A Language with Power
Swift is a robust and intuitive programming language developed by Apple for iOS, Mac, Apple TV, and Watch OS app development. Swift is easy-to-use and open-source, allowing a large community of developers to contribute, resulting in versatile and dynamic functionalities.
UIKit: Meeting Interface Goals
At the heart of this topic, lies the UIKit framework which provides a set of tools and infrastructure to construct and manage a graphical, event-driven user interface for iOS applications. It provides a window and view architecture for managing user interaction.
Understanding The Delayed Dismissal of a View Controller
let when = DispatchTime.now() + .seconds(5)
DispatchQueue.main.asyncAfter(deadline: when) {
self.dismiss(animated: true, completion: nil)
}
In the code sample above, the built-in function asyncAfter(deadline:qos:flags:execute:) executes a closure on the main queue after a specified period. This operation does not block the current thread, thus allowing smooth user interaction.
The Step-by-step Process
First, we specify the delay. The dispatchTime provides us an easy way to define this, by taking in the current time with DispatchTime.now() and adding the number of seconds we want to delay.
The DispatchQueue.main.asyncAfter(deadline:execute:) function then executes a block of code after a specified time. DispatchQueue represents an object that manages the execution of tasks serially or concurrently on your app’s main thread or on a background thread.
The highlighted section, ‘self.dismiss(animated: true, completion: nil)’ commences the dismissal of the view after the set duration. Here, self points to the current view controller, and dismiss is the function called to discard it, or more specifically, to dismiss it and optionally executes completion handler.
Functions and Libraries Involved
Swift’s DispatchQueue and DispatchTime are key players in the delayed dismissal of a view controller. They assist in managing the timing and execution of functions and closures.
Understanding how to manipulate the Dispatch framework will broaden your control over the timing of events. Mastering this skill can greatly enhance your ability to develop sophisticated, user-friendly iOS applications that provide a seamless experience for your users.
## UIResponder chain
Another critical topic is the UIResponder chain. The UIResponder class in UIKit defines an interface for objects that respond to and handle events. It is the base class for application-specific objects that respond to user input events and encapsulates the state-specific behavior.
## NSOperation
NSOperation and NSOperationQueue in the Foundation framework offers an object-oriented API for handling threads and executing operations in parallel. It encapsulates the concept of concurrent operations into a distinct abstraction layer. Combining these tools helps in crafting flexible and efficient iOS applications.
In conclusion, understanding how to delay the dismissal of a view controller involves harnessing the power of Swift’s DispatchQueue and DispatchTime. By utilizing these two powerful tools, developers can command when specific blocks of code are executed, resulting in a more enjoyable user experience all around.
