Separating multiple if conditions with commas in Swift

In Swift 3, the where keyword in condition clauses were replaced by a comma instead.

So a statement like if 1 == 1, 2 == 2 {} is saying "if 1 equals 1 where 2 equals 2..."

It's probably easiest to read a conditional statement with an && instead of a ,, but the results are the same.

You can read more about the details of the change in Swift 3 in the Swift Evolution proposal: https://github.com/apple/swift-evolution/blob/master/proposals/0099-conditionclauses.md

When it comes to evaluating boolean comma-separated conditions, the easies way to think of a comma is a pair or brackets. So, if you have

if true, false || true {}

It gets transformed into

if true && (false || true) {}

Actually the result is not the same. Say that you have 2 statements in an if and && between them. If in the first one you create a let using optional binding, you won't be able to see it in the second statement. Instead, using a comma, you will.

Comma example:

if let cell = tableView.cellForRow(at: IndexPath(row: n, section: 0)), cell.isSelected {
    //Everything ok
}

&& Example:

if let cell = tableView.cellForRow(at: IndexPath(row: n, section: 0)) && cell.isSelected {
    //ERROR: Use of unresolved identifier 'cell'              
}

Hope this helps.