Comparing elements at different indices in array Swift

In swift, I want to compare two different indexes in the same array. Right now, My code is something like:

var myArray:[String] = ["1" , "1", "2"]

for i in myArray{
     if(myArray[i] == myArray[i + 1]){
     // do something
     } 
}

From this, I get an error:

Cannot convert value of type 'String' to expected argument type 'Int'

How do I go about fixing this?

>Solution :

For-each construction (for i in array) does not provide you with an index, it takes elements from a sequence.

You may want to use ranges like this to aquire indices:
for i in 0 ..< array.count