Swift内置函数Reference

Swift语言提供了许多方便的内置函数，如countElements，join，max，reverse等。下面是一个清单，供以后查阅。

http://swift-ios.co/standard-functions-in-swift/

Standard functions in Swift

 June 17, 2014  admin  Uncategorized

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.

abs(signedNumber): Returns the absolute value of a given signed number. Trivial but not documented.

abs(-1) == 1abs(-42) == 42abs(42) == 42

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") == truecontains(languages, "Java") == falsecontains([29, 85, 42, 96, 75], 42) == true

dropFirst(sequence): Returns a new sequence (such as an array) without the first element of the sequence.

var 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.

var languages = ["Swift", "Objective-C"]var newLanguages = dropLast(languages)equal(newLanguages, ["Swift"]) == true

dump(object): Dumps the contents of an object to standard output.

var 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.

var languages = ["Swift", "Objective-C"]equal(languages, ["Swift", "Objective-C"]) == truevar 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(1...100, { $0 % 10 == 0 }) {    // 10, 20, 30, ...    println(i)    assert(contains([10, 20, 30, 40, 50, 60, 70, 80, 90, 100], 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.

var languages = ["Swift", "Objective-C"]find(languages, "Objective-C") == 1find(languages, "Java") == nilfind([29, 85, 42, 96, 75], 42) == 2

indices(sequence): Returns the indices (zero indexed) of the elements in the given sequence.

equal(indices([29, 85, 42]), [0, 1, 2])for i in indices([29, 85, 42]) {    // 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"var 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(1...3, { $0 * 5 }), [5, 10, 15])for i in map(1...10, { $0 * 10 }) {    // 10, 20, 30, ...    println(i)    assert(contains([10, 20, 30, 40, 50, 60, 70, 80, 90, 100], i))}

max(comparable1, comparable2, etc.): Returns the largest of the arguments given to the function.

max(0, 1) == 1max(8, 2, 3) == 8

maxElement(sequence): Returns the largest element in a supplied sequence of comparable elements.

maxElement(1...10) == 10var languages = ["Swift", "Objective-C"]maxElement(languages) == "Swift"

minElements(sequence): Returns the smallest element in a supplied sequence of comparable elements.

minElement(1...10) == 1var 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.

var languages = ["Swift", "Objective-C"]reduce(languages, "", { $0 + $1 }) == "SwiftObjective-C"reduce([10, 20, 5], 1, { $0 * $1 }) == 1000

reverse(sequence): Returns the elements of the given sequence reversed.

equal(reverse([1, 2, 3]), [3, 2, 1])for i in reverse([1, 2, 3]) {    // 3, 2, 1    println(i)}

startsWith(sequence1, sequence2): Return true if the starting elements sequence1 are equal to the of sequence2.

startsWith("foobar", "foo") == truestartsWith(10..100, 10..15) == truevar languages = ["Swift", "Objective-C"]startsWith(languages, ["Swift"]) == true

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.

Happy Swifting!

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(...)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(...)