Control Flow

For In Loop in Swift

The for-in loop iterates through every element in a collection (array, set, or dictionary) without specifying size. It behaves like a for each in other languages.

The C-style for loop is now deprecated in Swift. To emulate the C-style for loop, use a range as the collection.

Syntax

//temporary iterator implicitly declared in the loop
for iteratorVariable in collectionName {
    //the individual element is held in the iterator variable
    //to access the value, just use iteratorVariable
}

//C-style for loop behavior, start...finish provides the range and increments the iterator by 1
for iteratorVariable in start...finish {

}

Notes

For a dictionary, the two iterator variables are provided in brackets, separated by comma (key, value).

Example

var studentGrades: [Integer] = [50, 89, 75]; 

for grade in studentGrades { 
    print "Grade: \(grade)"
} //prints each value of the array studentGrades (each loop is an element of studentGrades assigned to grade variable)

See Also

The Swift Programming Language - Control Flow