Cannot find String.format in Kotlin Multiplatform shared module

Question

I find this weird. I am trying to use String.format in my shared module code in a Kotlin Multiplatform setup. It cannot find the format function and does not autocomplete in Android Studio. But it is working fine in the androidMain module.

Answer 1

IIRC, format needs platform localization info. KMP does not directly support localization. That function is available for the JVM (or Android) code. You'll need to do some kind of expect/actual, or find some kind of library that does this, although I don't know of any off-hand.

Answer 2

You can use NSString.stringWithFormat for Ios. Example:

Common:

expect fun formatTime(seconds: Long): String

Android:

actual fun formatTime(seconds: Long): String {
    val minutes = java.util.concurrent.TimeUnit.SECONDS.toMinutes(seconds)
    val remainingSeconds = seconds % 60
    return String.format("%02d:%02d", minutes, remainingSeconds)
}

Ios:

import platform.Foundation.NSString
import platform.Foundation.stringWithFormat

actual fun formatTime(seconds: Long): String {
    val minutes = seconds / 60
    val remainingSeconds = seconds % 60
    return NSString.stringWithFormat("%02d:%02d", minutes, remainingSeconds)
}