![]() You can follow this issue in YouTrack under KT-10455. If you squint, you’ll see a faint squiggly underline in IDEA when you use this in a constructor. Of the three issues I’ve mentioned, this is the only one that currently generates any kind of warning. If the function or property is non-final, it can end up executing code in a subclass before the subclass properties have been initialized. Using any function or property of the current class is effectively a reference to this. But you don’t need to explicitly use the word this to run into the problem. The this keyword refers to the current object, and inside the constructor it goes without saying that the current object is still in the middle of being constructed. iOS: SwiftIU Web: React Desktop: Compose for Desktop All data changes (states) and events we can easily manage by shared Kotlin Multiplatform ViewModel in MVVM architecture. It shouldn’t be surprising that using this in a constructor can have strange behaviour. The greeting property doesn’t have a value, because it hasn’t been initialized yet. But at the moment when toString is called, we’re still in the middle of initialising the Greeter superclass. That function is overridden by the concrete Hello subclass, and its implementation tries to access the greeting property. In the Greeter example, the call to println implicitly calls toString on the current object. Once that’s done, initialization proceeds down the object’s class hierarchy, filling in the properties of each class in order. Kotlin took Android's new UI framework, Jetpack Compose, and is. In the next 6-12 months, I think this will be more possible. I've heard some people create the UIs programmatically, but at this point, I imagine that's more rare. When you create a new object, its topmost superclass is initialized first. The UI for iOS apps is primarily made with Story Boards now, and you can't use Story Boards (easily) with Kotlin. As the product name, specify simpleLoginIOS and click Next. Select a template for an iOS app and click Next. Create an iOS project in Xcode In Xcode, click File New Project. The problem exists there too, and it has to do with the order that classes and their properties are initialized. Connect the framework to your iOS project. This might be the most counterintuitive of the three issues, but it’s probably also the most familiar to anyone who’s worked with Java. In reality, it throws a NullPointerException. This is the result of trying to access a drawable via painterResource (id R.drawable.icicon).
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