CODEWITHSUNDEEP
swift
Doug Smith
Doug Smith

Reputation: 29316

What is wrong with this array filter call in Swift?

var arr = [4, 5, 23, 4, 5, 2, 3]
arr.filter({
    return true
})

I get the error 'Int' is not a subtype of (). What am I doing wrong? Everything I've read seems to indicate this should work.

Upvotes: 0

Views: 134

Answers (2)

Jason W
Jason W

Reputation: 13179

You have to provide an index to the filter:

arr.filter({
    n in true
})

Upvotes: 0

matt
matt

Reputation: 534950

var arr = [4, 5, 23, 4, 5, 2, 3]
let arr2 = arr.filter {
    _ in
    return true
}

Problems with your original code:

  • filter returns an array. If you don't capture it, nothing useful happens. Notice that I've captured it in another variable; you could also reassign to the original variable.

  • If a parameter is passed into an anonymous function, you must capture it. You can capture it namelessly, as here, or with a name, or as $0, but you cannot completely ignore it; you must acknowledge it. That is what my _ in does.

Upvotes: 2

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