While using SwiftUI for building UIs, sooner or later we would like to write some unit-tests as well. Of course, we could always go for UI-tests, but these are much slower and therefore not so scalable if we would just want to have a basic verification for our view. It is easy to get going with writing unit-tests for UIKit code, but it is much more difficult for SwiftUI views. Currently, there seems to be two main ways: snapshot testing using the pointfreeco’s library or inspecting views with ViewInspector. Today,… Read more Basic unit-tests for SwiftUI view with ViewInspector →
Sometimes we need to handle delegates in a class which has the @MainActor annotation. Often it can be a view model where we expect that code runs on the main… Read more Wrapping delegates for @MainActor consumers in Swift →
While I was working on a mixed UIKit and SwiftUI project, I needed a way to access the UIHostingController within the SwiftUI view so that I could use it for interacting with other UIKit methods. This blog post tackles the problem and provides a simple solution how to implement it. The approach we are taking is using the SwiftUI environment and inserting an object into the environment, which then keeps a weak reference to the view controller hosting the SwiftUI view. Using the SwiftUI view environment has a benefit of… Read more Accessing UIHostingController from a SwiftUI view →
SwiftUI has view modifiers like onAppear() and onDisappear() for letting the view know when it is going to be displayed and when it is removed from the screen. In addition, there is a task() view modifier for running async functions. Something to keep in mind with onAppear() and task() is that the closure passed into the view modifier can be called multiple times when the view hierarchy changes. For example, when we have a TabView then the view receives onAppear() callback and also the task part of the task() is… Read more View modifier for preparing view data in SwiftUI →
LibraryContentProvider protocol in Xcode is a way for adding custom views and view modifiers to the Xcode library, which enables drag and dropping them to the SwiftUI preview. Xcode automatically… Read more LibraryContentProvider in Xcode →
Recently I was asked a question about creating an app which has SwiftUI views but no navigation logic in it. Instead, UIKit controls how views are presented. It is a fair question since SwiftUI views have navigation support, but not everything is there if we need to support previous iOS versions as well, or we have a case of an app which have both UIKit and SwiftUI views. Therefore, let’s take a look at on one approach, how to handle navigation on the UIKit side but still use SwiftUI views.… Read more UIKit navigation with SwiftUI views →
SwiftUI has a Picker view available with multiple different styles. One example of when it falls short is when we want to use a multi component picker with wheel style. One way how to try to achieve this is using a HStack with two Picker views, but it does not work very well, especially when trying to show it inside a Form view. So what else we can do? If something can’t be done in SwiftUI then we can use UIKit instead. In my case, I wanted to create a… Read more Using a multi component picker in a SwiftUI form →
If we want to spice up the user interface, then we can make some titles in the app to use gradient colours. In WWDC’21 Apple introduced an API for making gradient text styles easy to create. The .foregroundStyle() view modifier takes in a type which conforms to ShapeStyle protocol. One of these types are gradient types in SwiftUI. Therefore, creating a fun gradient text is a matter of creating a text and applying a foregroundStyle view modifier with a gradient on it. The new view modifier is great, but it… Read more Gradient text in SwiftUI →
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