Bool
A value type whose instances are either true or false.
@frozen struct BoolBool represents Boolean values in Swift. Create instances of Bool by using one of the Boolean literals true or false, or by assigning the result of a Boolean method or operation to a variable or constant.
var godotHasArrived = false
let numbers = 1...5
let containsTen = numbers.contains(10)
print(containsTen)
// Prints "false"
let (a, b) = (100, 101)
let aFirst = a < b
print(aFirst)
// Prints "true"Swift uses only simple Boolean values in conditional contexts to help avoid accidental programming errors and to help maintain the clarity of each control statement. Unlike in other programming languages, in Swift, integers and strings cannot be used where a Boolean value is required.
For example, the following code sample does not compile, because it attempts to use the integer i in a logical context:
var i = 5
while i {
print(i)
i -= 1
}
// error: Cannot convert value of type 'Int' to expected condition type 'Bool'The correct approach in Swift is to compare the i value with zero in the while statement.
while i != 0 {
print(i)
i -= 1
}Using Imported Boolean values
The C bool and Boolean types and the Objective-C BOOL type are all bridged into Swift as Bool. The single Bool type in Swift guarantees that functions, methods, and properties imported from C and Objective-C have a consistent type interface.
Citizens in Swift
Conformances
protocol CVarArgA type whose instances can be encoded, and appropriately passed, as elements of a C
va_list.protocol CustomReflectableA type that explicitly supplies its own mirror.
protocol CustomStringConvertibleA type with a customized textual representation.
protocol DecodableA type that can decode itself from an external representation.
protocol EncodableA type that can encode itself to an external representation.
protocol EquatableA type that can be compared for value equality.
protocol ExpressibleByBooleanLiteralA type that can be initialized with the Boolean literals
trueandfalse.protocol HashableA type that can be hashed into a
Hasherto produce an integer hash value.protocol LosslessStringConvertibleA type that can be represented as a string in a lossless, unambiguous way.
protocol SendableA type whose values can safely be passed across concurrency domains by copying.
Members
init() Creates an instance initialized to
false.init(Bool) Creates an instance equal to the given Boolean value.
init?(String) Creates a new Boolean value from the given string.
init(booleanLiteral: Bool) Creates an instance initialized to the specified Boolean literal.
init(from: Decoder) throws Creates a new instance by decoding from the given decoder.
static func random() -> Bool Returns a random Boolean value.
static func random<T>(using: inout T) -> Bool Returns a random Boolean value, using the given generator as a source for randomness.
var customMirror: MirrorA mirror that reflects the
Boolinstance.var description: StringA textual representation of the Boolean value.
static func ! (Bool) -> Bool Performs a logical NOT operation on a Boolean value.
static func && (Bool, () throws -> Bool) rethrows -> Bool Performs a logical AND operation on two Boolean values.
static func == (Bool, Bool) -> Bool static func || (Bool, () throws -> Bool) rethrows -> Bool Performs a logical OR operation on two Boolean values.
func encode(to: Encoder) throws Encodes this value into the given encoder.
func hash(into: inout Hasher) Hashes the essential components of this value by feeding them into the given hasher.
func toggle() Toggles the Boolean variable’s value.
var customPlaygroundQuickLook: _PlaygroundQuickLookA custom playground Quick Look for the
Boolinstance.
Features
Available in Foundation
Members
Extension in BSON
Conformances
Features
Extension in MultipartKit
Conformances
Members
Extension in ArgumentParser
Conformances
protocol ExpressibleByArgumentA type that can be expressed as a command-line argument.
Extension in SwiftASN1
Conformances
protocol DERImplicitlyTaggableAn ASN.1 node that can tolerate having an implicit tag.
protocol DERParseableDefines a type that can be parsed from a DER-encoded form.
protocol DERSerializableDefines a type that can be serialized in DER-encoded form.
Members
init(derEncoded: ASN1Node, withIdentifier: ASN1Identifier) throws static var defaultIdentifier: ASN1Identifierfunc serialize(into: inout DER.Serializer, withIdentifier: ASN1Identifier) throws
Features
init(asn1Any: ASN1Any) throws Construct this node from an ASN.1 ANY object.
init(asn1Any: ASN1Any, withIdentifier: ASN1Identifier) throws Construct this node from an ASN.1 ANY object.
Extension in Atomics
Conformances
protocol AtomicValueA type that supports atomic operations through a separate atomic storage representation.
Members
Extension in JSONDecoding
Conformances
protocol JSONDecodableA type that can be decoded from a JSON variant value.
Members
Extension in JSONEncoding
Conformances
protocol JSONEncodableA type that can be encoded to a JSON variant value.
Members
Extension in BSONDecoding
Conformances
protocol BSONDecodableA type that can be decoded from a BSON variant value backed by some type of storage not particular to the decoded type.
Members
Extension in BSONEncoding
Conformances
protocol BSONEncodableA type that can be encoded to a BSON variant value.
Members
Extension in NIOConcurrencyHelpers
Conformances
protocol AtomicPrimitiveThe protocol that all types that can be made atomic must conform to.
protocol NIOAtomicPrimitiveThe protocol that all types that can be made atomic must conform to.
Members
static let atomic_add: (OpaquePointer, Bool) -> Boolstatic let atomic_compare_and_exchange: (OpaquePointer, Bool, Bool) -> Boolstatic let atomic_create: (Bool) -> OpaquePointerstatic let atomic_destroy: (OpaquePointer) -> Voidstatic let atomic_exchange: (OpaquePointer, Bool) -> Boolstatic let atomic_load: (OpaquePointer) -> Boolstatic let atomic_store: (OpaquePointer, Bool) -> Voidstatic let atomic_sub: (OpaquePointer, Bool) -> Boolstatic let nio_atomic_add: (UnsafeMutablePointer<catmc_nio_atomic__Bool>, Bool) -> Boolstatic let nio_atomic_compare_and_exchange: (UnsafeMutablePointer<catmc_nio_atomic__Bool>, Bool, Bool) -> Boolstatic let nio_atomic_create_with_existing_storage: (UnsafeMutablePointer<catmc_nio_atomic__Bool>, Bool) -> Voidstatic let nio_atomic_exchange: (UnsafeMutablePointer<catmc_nio_atomic__Bool>, Bool) -> Boolstatic let nio_atomic_load: (UnsafeMutablePointer<catmc_nio_atomic__Bool>) -> Boolstatic let nio_atomic_store: (UnsafeMutablePointer<catmc_nio_atomic__Bool>, Bool) -> Voidstatic let nio_atomic_sub: (UnsafeMutablePointer<catmc_nio_atomic__Bool>, Bool) -> Booltypealias AtomicWrapper
Extension in SwiftSyntaxBuilder
Conformances
protocol ExpressibleByLiteralSyntaxA Swift type whose value can be represented directly in source code by a Swift literal.
Members
Extension in JSONDecoding
Conformances
protocol JSONDecodableA type that can be decoded from a JSON variant value.
Members
Extension in JSONEncoding
Conformances
Members
Extension in Vapor
Conformances
protocol AsyncRequestDecodableCan convert
Requestto aSelf.protocol AsyncResponseEncodableCan convert
selfto aResponse.protocol ContentConvertible to / from content in an HTTP message.
protocol RequestDecodableCan convert
Requestto aSelf.protocol ResponseEncodableCan convert
selfto aResponse.
Features
func encodeResponse(status: HTTPStatus, headers: HTTPHeaders, for: Request) -> EventLoopFuture<Response> Asynchronously encodes
Selfinto aResponse, setting the supplied status and headers.