I remember kmm used to have some restrictions having default

Question

I remember kmm used to have some restrictions having default arguments and swift objective c Is it still a case Recently I tried that out and it seem that kotlin native compiler does respsect function with default argument So this ```fun sendMessage text String customAttributes Map lt String String gt = emptyMap ``` translated to this ```func sendMessage text String customAttributes String String = ``` Am I seeing write kotlin 1 6 10

kpgalligan · Answer

```func sendMessage text String customAttributes String String = ``` That s swift The Kotlin compiler would be generating objc Where do you see that Default parameters aren t available unless something I m not aware of happened

Anton Afanasev · Answer

That is really odd I would expect to see Kotlin compiler generating obj c as well Instead I am seeing a swift generated code I see that by using the regular XCode `Jump To Definition` tool Thats weird

Anton Afanasev · Answer

Interestingly if I pass an empty map as a default argument swift would not force me to provide a value for this argument So I can do something like that common ```fun sendMessage text String customAttributes Map lt String String gt = emptyMap ``` ios swift ```client sendMessage text Hello ``` No warnings or errors But that only work with emptyMap If I go and define some other default argument lets say ```fun sendMessage text String customAttributes Map lt String String gt = mapOf a to b ``` They default argument will be ignored and the value of `customAttributes` in that case will be empty map as well Is it possible that K N compiler always treat a map argument as an emptyMap unless actual value is provided

Rick Clephas · Answer

Cool Didn t know about this This is actually part of the Swift ObjC interop gt An argument whose Objective C type is an NSDictionary defaults to nil if the NSDictionary is nullable and if the NSDictionary is non nullable under the following conditions gt the argument label contains the word options or attributes or the two words user info one after another gt the argument label is empty and the method base name ends with the word options or attributes or the two words user info one after another <https github com apple swift blob main docs CToSwiftNameTranslation md default argument values>

Rick Clephas · Answer

Another nice one is gt A final argument that is a nullable function or block pointer defaults to nil ```fun doSomething block gt Unit = TODO ``` can be called from Swift like ```doSomething default nil doSomething ```

kpgalligan · Answer

Huh interesting

kpgalligan · Answer

I didn t know that either

Anton Afanasev · Answer

Thanks < Rick Clephas> and < kpgalligan> Thats a nice thing to know Sounds like some sort of `easter egg`