Range

A half-open interval over a comparable type, from a lower bound up to, but not including, an upper bound.

You create Range instances by using the half-open range operator (..<).

  • let underFive = 0.0..<5.0

You can use a Range instance to quickly check if a value is contained in a particular range of values. For example:

  • print(underFive.contains(3.14))     // Prints "true"
  • print(underFive.contains(6.28))     // Prints "false"
  • print(underFive.contains(5.0))      // Prints "false"

Range instances can represent an empty interval, unlike ClosedRange.

  • let empty = 0.0..<0.0
  • print(empty.contains(0.0))          // Prints "false"
  • print(empty.isEmpty)                // Prints "true"

See Also: CountableRange, ClosedRange, CountableClosedRange

Inheritance CustomDebugStringConvertible, CustomReflectable, CustomStringConvertible, Equatable View Protocol Hierarchy →
Import
  • import Swift

Initializers

init(_: ClosedRange<Bound>)

Creates an instance equivalent to the given range.

An equivalent range must be representable as an instance of Range. For example, passing a closed range with an upper bound of Int.max triggers a runtime error, because the resulting half-open range would require an upper bound of Int.max + 1, which is not representable as an Int.

other: A range to convert to a Range instance.

Declaration

init(_: CountableClosedRange<Bound>)

Creates an instance equivalent to the given range.

An equivalent range must be representable as an instance of Range. For example, passing a closed range with an upper bound of Int.max triggers a runtime error, because the resulting half-open range would require an upper bound of Int.max + 1, which is not representable as an Int.

other: A range to convert to a Range instance.

Declaration

init(_: CountableRange<Bound>)

Creates an instance equivalent to the given range.

other: A range to convert to a Range instance.

Declaration

init(_: Range<Bound>)

Creates an instance equivalent to the given range.

other: A range to convert to a Range instance.

Declaration

  • init(_ other: Range<Bound>)
init(uncheckedBounds bounds: (lower: Bound,:)

Creates an instance with the given bounds.

Because this initializer does not perform any checks, it should be used as an optimization only when you are absolutely certain that lower is less than or equal to upper. Using the half-open range operator (..<) to form Range instances is preferred.

bounds: A tuple of the lower and upper bounds of the range.

Declaration

  • init(uncheckedBounds bounds: (lower: Bound, upper: Bound))

Instance Variables

var count: Bound.Stride

The number of values contained in the range.

Declaration

  • var count: Bound.Stride { get }
var customMirror: Mirror

The custom mirror for this instance.

If this type has value semantics, the mirror should be unaffected by subsequent mutations of the instance.

Declaration

  • var customMirror: Mirror { get }
var debugDescription: String

A textual representation of the range, suitable for debugging.

Declaration

  • var debugDescription: String { get }
var description: String

A textual representation of the range.

Declaration

  • var description: String { get }
var isEmpty: Bool

A Boolean value indicating whether the range contains no elements.

An empty Range instance has equal lower and upper bounds.

  • let empty: Range = 10..<10
  • print(empty.isEmpty)
  • // Prints "true"

Declaration

  • var isEmpty: Bool { get }
var lowerBound: Bound

The range's lower bound.

In an empty range, lowerBound is equal to upperBound.

Declaration

  • var lowerBound: Bound { get }
var upperBound: Bound

The range's upper bound.

In an empty range, upperBound is equal to lowerBound. A Range instance does not contain its upper bound.

Declaration

  • var upperBound: Bound { get }

Instance Methods

func ==(_:rhs:)

Returns a Boolean value indicating whether two values are equal.

Equality is the inverse of inequality. For any values a and b, a == b implies that a != b is false.

Parameters: lhs: A value to compare. rhs: Another value to compare.

Declaration

func ~=(_:value:)

Declaration

  • func ~=(pattern: Range<Bound>, value: Bound) -> Bool
func clamped(to:)

Returns a copy of this range clamped to the given limiting range.

The bounds of the result are always limited to the bounds of limits. For example:

  • let x: Range = 0..<20
  • print(x.clamped(to: 10..<1000))
  • // Prints "10..<20"

If the two ranges do not overlap, the result is an empty range within the bounds of limits.

  • let y: Range = 0..<5
  • print(y.clamped(to: 10..<1000))
  • // Prints "10..<10"

limits: The range to clamp the bounds of this range. Returns: A new range clamped to the bounds of limits.

Declaration

  • func clamped(to limits: Range<Bound>) -> Range<Bound>
func contains(_:)

Returns a Boolean value indicating whether the given element is contained within the range.

Because Range represents a half-open range, a Range instance does not contain its upper bound. element is contained in the range if it is greater than or equal to the lower bound and less than the upper bound.

element: The element to check for containment. Returns: true if element is contained in the range; otherwise, false.

Declaration

  • func contains(_ element: Bound) -> Bool
func overlaps(_: ClosedRange<Bound>)

Returns a Boolean value indicating whether this range and the given range contain an element in common.

This example shows two overlapping ranges:

  • let x: Range = 0..<20
  • print(x.overlaps(10...1000 as ClosedRange))
  • // Prints "true"

Because a half-open range does not include its upper bound, the ranges in the following example do not overlap:

  • let y: ClosedRange = 20..<30
  • print(x.overlaps(y))
  • // Prints "false"

other: A range to check for elements in common. Returns: true if this range and other have at least one element in common; otherwise, false.

Declaration

func overlaps(_: CountableClosedRange<Bound>)

Returns a Boolean value indicating whether this range and the given range contain an element in common.

This example shows two overlapping ranges:

Because a half-open range does not include its upper bound, the ranges in the following example do not overlap:

other: A range to check for elements in common. Returns: true if this range and other have at least one element in common; otherwise, false.

Declaration

func overlaps(_: CountableRange<Bound>)

Returns a Boolean value indicating whether this range and the given range contain an element in common.

This example shows two overlapping ranges:

Because a half-open range does not include its upper bound, the ranges in the following example do not overlap:

other: A range to check for elements in common. Returns: true if this range and other have at least one element in common; otherwise, false.

Declaration

func overlaps(_: Range<Bound>)

Returns a Boolean value indicating whether this range and the given range contain an element in common.

This example shows two overlapping ranges:

  • let x: Range = 0..<20
  • print(x.overlaps(10..<1000 as Range))
  • // Prints "true"

Because a half-open range does not include its upper bound, the ranges in the following example do not overlap:

  • let y: Range = 20..<30
  • print(x.overlaps(y))
  • // Prints "false"

other: A range to check for elements in common. Returns: true if this range and other have at least one element in common; otherwise, false.

Declaration