A value type whose instances are either true or false.
Language
- Swift
Overview
Bool represents Boolean values in Swift. Create instances of Bool by using one of the Boolean literals true and 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 other programming languages, in Swift integers and strings cannot be used where a Boolean value is expected.
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
}
The correct approach in Swift is to compare the i value with zero in the while statement.
while i != 0 {
print(i)
i -= 1
}