Swift has 74 built-in functions but only seven of them are documented in the Swift book (“The Swift Programming Language”). The rest remain undocumented. This article lists all built-in Swift functions – both documented and undocumented ones. The definition used for “built-in function” used in this article is a function available in Swift without importing any modules (such as Foundation, etc.) or referencing any classes. Let’s start with the seven documented built-in functions mentioned in the Swift book along with the page number on which the function was first mentioned:
Below is the full list of all 74 built-in functions in Swift. The functions covered above are the ones I think are useful on a day-to-day basis, but perhaps I’ve missed some functions from the list below that deserves coverage. If so, let me know in the comments section and please include a short code snippet to show how to use the function.
abs(...)
advance(...)
alignof(...)
alignofValue(...)
assert(...)
bridgeFromObjectiveC(...)
bridgeFromObjectiveCUnconditional(...)
bridgeToObjectiveC(...)
bridgeToObjectiveCUnconditional(...)
c_malloc_size(...)
c_memcpy(...)
c_putchar(...)
contains(...)
count(...)
countElements(...)
countLeadingZeros(...)
debugPrint(...)
debugPrintln(...)
distance(...)
dropFirst(...)
dropLast(...)
dump(...)
encodeBitsAsWords(...)
enumerate(...)
equal(...) 目前我知道equal可以判断两个数组是否相等
filter(...)
find(...)
getBridgedObjectiveCType(...)
getVaList(...)
indices(...)
insertionSort(...)
isBridgedToObjectiveC(...)
isBridgedVerbatimToObjectiveC(...)
isUniquelyReferenced(...)
join(...)
lexicographicalCompare(...)
map(...)
max(...)
maxElement(...)
min(...)
minElement(...)
numericCast(...)
partition(...)
posix_read(...)
posix_write(...)
print(...)
println(...)
quickSort(...)
reduce(...)
reflect(...)
reinterpretCast(...)
reverse(...)
roundUpToAlignment(...)
sizeof(...)
sizeofValue(...)
sort(...)
split(...)
startsWith(...)
strideof(...)
strideofValue(...)
swap(...)
swift_MagicMirrorData_summaryImpl(...)
swift_bufferAllocate(...)
swift_keepAlive(...)
toString(...)
transcode(...)
underestimateCount(...)
unsafeReflect(...)
withExtendedLifetime(...)
withObjectAtPlusZero(...)
withUnsafePointer(...)
withUnsafePointerToObject(...)
withUnsafePointers(...)
withVaList(...)
// assert mentioned on page 55
assert(true)
// countElements mentioned on page 79 原来是countElement现在是count
count("foo") ==
// enumerate mentioned on page 94
for (i, j) in enumerate(["A", "B"]) {
// "0:A", "1:B" will be printed
println("\(i):\(j)")
}
// min mentioned on page 246
min(, , ) ==
// print mentioned on page 85
print("Hello ")
// println mentioned on page 4
println("World")
// sort mentioned on page 14
var a = ["B","A"]
sort(&a)
for i in a {
// "A", "B" will be printed
println(i)
}
abs(signedNumber): Returns the absolute value of a given signed number. Trivial but not documented.
abs(-) ==
abs(-) ==
abs() ==
contains(sequence, element): Returns true if a given sequence (such as an array) contains the specified element.
var languages = ["Swift", "Objective-C"]
contains(languages, "Swift") == true
contains(languages, "Java") == false
contains([, , , , ], ) == true
dropFirst(sequence): Returns a new sequence (such as an array) without the first element of the sequence.
languages = ["Swift", "Objective-C"]
var oldLanguages = dropFirst(languages)
equal(oldLanguages, ["Objective-C"]) == true
dropLast(sequence): Returns a new sequence (such as an array) without the last element of the sequence passed as argument to the function.
languages = ["Swift", "Objective-C"]
var newLanguages = dropLast(languages)
equal(newLanguages, ["Swift"]) == true
dump(object): Dumps the contents of an object to standard output.
languages = ["Swift", "Objective-C"]
dump(languages)
// Prints:
// ▿ 2 elements
// - [0]: Swift
// - [1]: Objective-C
equal(sequence1, sequence2): Returns true if sequence1 and sequence2 contain the same elements.
languages = ["Swift", "Objective-C"]
equal(languages, ["Swift", "Objective-C"]) == true
oldLanguages = dropFirst(languages)
equal(oldLanguages, ["Objective-C"]) == true
filter(sequence, includeElementClosure): Returns a the elements from sequence that evaluate to true by includeElementClosure.
for i in filter(..., { $ % == }) {
// 10, 20, 30, ...
println(i)
assert(contains([, , , , , , , , , ], i))
}
find(sequence, element): Return the index of a specified element in the given sequence. Or nil if the element is not found in the sequence.
languages = ["Swift", "Objective-C"]
find(languages, "Objective-C") ==
find(languages, "Java") == nil
find([, , , , ], ) ==
indices(sequence): Returns the indices (zero indexed) of the elements in the given sequence.
equal(indices([, , ]), [, , ])
for i in indices([, , ]) {
// 0, 1, 2
println(i)
}
join(separator, sequence): Returns the elements of the supplied sequence separated by the given separator.
join(":", ["A", "B", "C"]) == "A:B:C"
languages = ["Swift", "Objective-C"]
join("/", languages) == "Swift/Objective-C"
map(sequence, transformClosure): Returns a new sequence with the transformClosure applied to all elements in the supplied sequence.
equal(map(..., { $ * }), [, , ])
for i in map(..., { $ * }) {
// 10, 20, 30, ...
println(i)
assert(contains([, , , , , , , , , ], i))
}
max(comparable1, comparable2, etc.): Returns the largest of the arguments given to the function.
max(, ) ==
max(, , ) ==
maxElement(sequence): Returns the largest element in a supplied sequence of comparable elements.
maxElement(...) ==
languages = ["Swift", "Objective-C"]
maxElement(languages) == "Swift"
minElements(sequence): Returns the smallest element in a supplied sequence of comparable elements.
minElement(...) ==
languages = ["Swift", "Objective-C"]
minElement(languages) == "Objective-C"
reduce(sequence, initial, combineClosure): Recursively reduce the elements in sequence into one value by running the combineClosure on them with starting value of initial.这个玩意一点都不懂。
languages = ["Swift", "Objective-C"]
reduce(languages, "", { $ + $ }) == "SwiftObjective-C"
reduce([, , ], , { $ * $ }) ==
reverse(sequence): Returns the elements of the given sequence reversed.
equal(reverse([, , ]), [, , ])
for i in reverse([, , ]) {
// 3, 2, 1
println(i)
}
startsWith(sequence1, sequence2): Return true if the starting elements sequence1 are equal to the of sequence2.
startsWith("foobar", "foo") == true
startsWith(..., ...) == true
languages = ["Swift", "Objective-C"]
startsWith(languages, ["Swift"]) == true