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iOS Swift Basics (retired) Control Flow If Statement

Posted by Mahmoud Essa
Mahmoud Essa
1,173 Points

what is wrong in this let months = [1, 2, 3] for month in months { if months[month] == 1 { println("January") }}

let months = [1, 2, 3]

for month in months { if months[month] == 1 { println("January") } else if months[month] == 2 { println("February") } else if months[month] == 3 { println("March") } }

months.swift 
let months = [1, 2, 3]

for month in months
{
if months[month] == 1
{
println("January")
}
else if months[month] == 2
{
println("February")
}
else if months[month] == 3
{
println("March")
}
}

1 Answer

Steve Hunter
Steve Hunter
57,712 Points

Hi there,

When you use a for loop like this, the loop iterates through each element of the array and performs whatever code is inside the loop on each element in turn.

The loop uses a variable to hold each element in your case, that variable is month. So the line for month in months says to the compiler, "we're going to iterate through every element of the array months one element at a a time - put each element's value in the variable called month one by one."

So, where you have if months[month] == 1 what you really to put is if month == 1 as the vriable month with hold the value 1 on the first loop, 2 on the second, and so on. If you were using a more traditional for loop that was incrementing from zero, for example, you could then use months[i] but the use of the for/each/in construction means you can bypass that.

Please let me know if that makes sense else I'll try again!

Steve. 

let months = [1, 2, 3]

for month in months {
  if month == 1 {
    println("January")
  }
  else if month == 2 {
    println("February")
  }
  else if month == 3 {
    println("March")
  }
}