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SOLVED: Why doesn't the parameter name matter in this function's signature?

Forums > SwiftUI

I'm trying to marry up what I see in the developer documentation with what I have just written, just so's I fully understand next time I write something like:

ForEach(expenses.items, id: \.name) { item in
                .onDelete(perform: removeItems)

func removeItems(parameter1 offsets: IndexSet) {
        expenses.items.remove(atOffsets: offsets)

It doesn't seem to matter what symbol, or underscore, I substitute for parameter1, the function removeItems is successfully performed by the ForEach.onDelete(perform:) regardless of the parameter name in its signature.

Specifically, my question is about writing the signature of the function that is to be performed :

When I see

 @inlinable public func onDelete(perform action: ((IndexSet) -> Void)?) -> some DynamicViewContent

can I assume that I can, since my removeItemsfunction is being used as a closure - all Swift functions are closures, after all - that as long as it accepts one argument of type IndexSet, it doesn't matter what name I give to the corresponding parameter.

Actually, in posting this, I think I've answered my own question. Mostly.

I assume that, since there is no overloading of perform, and as it is being invoked as a closure, then there is no choice to be made between different signature "flavours" of perform and thus a parameter name is not important and any will do - so long as there is one that the function can use.


Yeah, what matters is the function signature, not so much the parameter names. So you have to supply a function with a signature of (IndexSet) -> Void but what you call that IndexSet parameter is totally up to you.


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