Iterate an array with index in Swift 3

Question

I'm trying to iterate an array with an index in Swift 3 but keep getting

Expression type '[Int]' is ambiguous without more context

this is reproducible with the following example in a playground:

var a = [Int]()
a.append(1)
a.append(2)
// Gives above error
for (index, value) in a {
  print("\(index): \(value)")
}

I'm not sure what context it is asking for.

Saying in a gives you one value (i.e. 1, or 2), not a tuple with both an index and a value. — matt
– matt, Commented Nov 1, 2016 at 1:27
Can anyone help me understand why this question received a downvote? How can I improve it? — Friedrich 'Fred' Clausen
– Friedrich 'Fred' Clausen, Commented Nov 1, 2016 at 1:29
It's so careless. for (index,value) in a, when a is an array, is just silly talk. — matt
– matt, Commented Nov 1, 2016 at 1:30

NRitH · Accepted Answer · 2016-11-01 01:26:43Z

26

You forgot to call a.enumerated(), which is what gives you the (index, value) tuples. for value in a is what gives you each element without the index.

answered Nov 1, 2016 at 1:26

NRitH

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2 revs, 2 users 94% · Accepted Answer · 2017-11-22 19:56:31Z

4

Correct Code:

var a = [Int]()
a.append(1)
a.append(2)
// Gives above error
for (index, value) in a.enumerated() {
    print("\(index): \(value)")
}

edited Nov 22, 2017 at 19:56

community wiki

2 revs, 2 users 94%
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