What is this "in" keyword in this parameter declaration?

Question

Created Aug ’21

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override func numberOfSections(in tableView: UITableView) -> Int {
    return 0
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return 0
}

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Answer 1

DTS Engineer OP

Apple

Aug ’21

Accepted Answer

It's generally good practice to write readable code so that it's easy to follow and understand the implementation of a function with well-named parameters. Swift takes this a step further by ensuring that the call site to a function is also clearly readable with an argument label so the function call reads like a clear sentence. In your example, that argument label is in. The Swift Language Guide has more information on argument labels.

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