Creating Optional Parameters in KMM Data Class for iOS

Question:

How to create an optional parameter in a KMM data class for iOS?

Answer:

In Kotlin Multiplatform Mobile (KMM), you can create optional parameters in a data class by assigning default values to the properties. However, iOS does not natively support default parameter values in data classes like Kotlin does. To work around this limitation, you can use Kotlin's @JvmOverloads annotation to generate overloaded constructors with default parameter values for your data class.

Here's an example:

import kotlinx.serialization.Serializable

@Serializable
data class MyDataClass @JvmOverloads constructor(
    val property1: String,
    val property2: Int = 0, // Optional parameter with default value
    val property3: Boolean = false // Another optional parameter with default value
)
    

The @JvmOverloads annotation generates additional constructors for Java interoperability, allowing you to omit the optional parameters when creating instances of the data class in iOS.

Here's how you can create an instance of the MyDataClass in iOS:

let myData = MyDataClass(property1: "Value 1")
print(myData) // Output: MyDataClass(property1=Value 1, property2=0, property3=false)
    

In this example, the property2 and property3 are optional parameters with default values, so you don't need to specify them explicitly when creating the instance.

Note that you need to ensure that the @Serializable annotation is applied to the data class for serialization and deserialization purposes. Additionally, make sure you have the necessary dependencies and configuration in place for using Kotlin serialization in your KMM project.

Remember to rebuild your project to ensure the generated constructors are available for use in iOS.

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