How to Work with One-sided Ranges in Swift 4?

One-Sided ranges introduces a new protocol RangeExpresstion and a set of prefix/postfix operators to form one-sided ranges, i.e. ranges where either the lower or upper bound is unspecified.

Infinite Sequence : You can use the one-sided range to construct an infinite sequence and it's replacement of enumerated() so don't start with 0.

let rangesInfinite = 1...       // Infinite values
rangesInfinite.contains(3) .    // true
rangesInfinite.contains(569999) // true
rangesInfinite.contains(0)      // false

Collection subscripts : The collocation's startIndex/endIndex with lower/upper bound change to gets elements.

Before the Swift 4.0

let numbers = [1,2,3,4,5,6,7,8,9,10]
numbers[5..<numbers.endIndex]

Now in Swift 4.0

let numbers = [1,2,3,4,5,6,7,8,9,10]
numbers[5...]

Before the Swift 4.0

let numbers = [1,2,3,4,5,6,7,8,9,10]
numbers[0..<5]

Now in Swift 4.0

let numbers = [1,2,3,4,5,6,7,8,9,10]
numbers[..<5]

Pattern Matching : One-sided ranges also used in pattern matching constructs. its use in the case of switch statement.

let value = 8
switch value {
case 10...:
    print("greater than ten")
case 10:
    print("ten")
case ..<10:
    print("less than ten")
default:
    fatalError("unreachable")
}