Swift包含了74個(gè)內(nèi)置函數(shù)，但在 The Swift Programming Langage 一書中只介紹了其中的7個(gè)，其它的都沒(méi)有在文檔中體現(xiàn)。
這篇文章列舉出了所有的Swift庫(kù)函數(shù)。文中所謂的 內(nèi)置函數(shù) 是指無(wú)需引入任何模塊（比如說(shuō)Fundation等）即可以直接使用的函數(shù)。
下面先來(lái)看看7個(gè)在文檔中提到的庫(kù)函數(shù)：
下面列出一些很實(shí)用，但未在文檔中體現(xiàn)的庫(kù)函數(shù)：
//斷言，參數(shù)如果為`true`則繼續(xù)，否則拋出異常
//assert mentioned on page 55
assert(true)
//計(jì)算序列的元素個(gè)數(shù)
// countElements mentioned on page 79
countElements("foo") == 3
//返回一個(gè)新的序列，其中每個(gè)元素是一個(gè)元組，
//第一個(gè)值為原來(lái)元素所在的位置`index`，第二個(gè)為原來(lái)序列中的元素
// enumerate mentioned on page 94
for (i, j) in enumerate(["A", "B"]) {
// "0:A", "1:B" will be printed
println("/(i):/(j)")
}
//返回所有參數(shù)中的最小值
// min mentioned on page 246
min(8, 2, 3) == 2
//打印
// print mentioned on page 85
print("Hello ")
//打印（帶換行）
// println mentioned on page 4
println("World")
//排序
// sort mentioned on page 14
for i in sort(["B", "A"]) {
// "A", "B" will be printed
println(i)
}
abs(signedNumber)：返回?cái)?shù)字的絕對(duì)值
abs(-1) == 1
abs(-42) == 42
abs(42) == 42
contains(sequence, element)：如果某個(gè)序列sequence（比如說(shuō)一個(gè)數(shù)組）包含指定的元素element，則返回true，否則返回false。
var languages = ["Swift", "Objective-C"]
contains(languages, "Swift") == true
contains(languages, "Java") == false
contains([29, 85, 42, 96, 75], 42) == true
dropFirst(sequence)：返回一個(gè)去掉了首個(gè)元素的、新的序列（比如一個(gè)新數(shù)組）。
var languages = ["Swift", "Objective-C"]
var oldLanguages = dropFirst(languages)
equal(oldLanguages, ["Objective-C"]) == true
dropLast(sequence)：返回一個(gè)去掉了最后一個(gè)元素的、新的序列（比如一個(gè)新數(shù)組）。
var languages = ["Swift", "Objective-C"]
var newLanguages = dropLast(languages)
equal(newLanguages, ["Swift"]) == true
dump(object)：打印出某個(gè)對(duì)象object的所有信息
var languages = ["Swift", "Objective-C"]
dump(languages)
// Prints:
// ? 2 elements
// - [0]: Swift
// - [1]: Objective-C
equal(sequence1, sequence2)：判斷兩個(gè)序列是否相等
var languages = ["Swift", "Objective-C"]
equal(languages, ["Swift", "Objective-C"]) == true
var oldLanguages = dropFirst(languages)
equal(oldLanguages, ["Objective-C"]) == true
filter(sequence, includeElementClosure)：對(duì)序列sequence中每個(gè)元素都執(zhí)行includeElementClosure閉包，并將所有閉包結(jié)果為true的元素合成一個(gè)新序列sequence并返回。
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)：返回序列sequence中某元素element的位置index。如果序列中不存在此元素，則返回nil。
var languages = ["Swift", "Objective-C"]
find(languages, "Objective-C") == 1
find(languages, "Java") == nil
find([29, 85, 42, 96, 75], 42) == 2
indices(sequence)：返回序列sequence中所有元素的位置（indices是index的復(fù)數(shù)）
equal(indices([29, 85, 42]), [0, 1, 2])
for i in indices([29, 85, 42]) {
// 0, 1, 2
println(i)
}
join(separator, sequence)：將序列sequence通過(guò)分隔符separator連成一個(gè)字符串，并返回此字符串。
join(":", ["A", "B", "C"]) == "A:B:C"
var languages = ["Swift", "Objective-C"]
join("/", languages) == "Swift/Objective-C"
map(sequence, transformClosure)：對(duì)序列sequence中每個(gè)元素都執(zhí)行includeElementClosure閉包，并將所有閉包的結(jié)果合成一個(gè)新序列sequence并返回。
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.)：返回參數(shù)中的最大值。
max(0, 1) == 1
max(8, 2, 3) == 8
maxElement(sequence)：返回序列sequence中的最大值。
maxElement(1...10) == 10
var languages = ["Swift", "Objective-C"]
maxElement(languages) == "Swift"
minElements(sequence)：返回序列sequence中的最小值。
minElement(1...10) == 1
var languages = ["Swift", "Objective-C"]
minElement(languages) == "Objective-C"
reduce(sequence, initial, combineClosure)：給定一個(gè)序列sequence，以及一個(gè)初始值initial，然后將initial和序列里的第1個(gè)元素作為參數(shù)傳入combineClosure中進(jìn)行運(yùn)算，得到的結(jié)果保存到initial；然后再將initial和第2個(gè)元素傳入combineClosure中計(jì)算，結(jié)果保存到initial；重復(fù)計(jì)算直到所有sequence中的元素都計(jì)算完畢，并返回最終的initial值。
var languages = ["Swift", "Objective-C"]
reduce(languages, "", { $0 + $1 }) == "SwiftObjective-C"
reduce([10, 20, 5], 1, { $0 * $1 }) == 1000
reverse(sequence)：返回逆序的序列sequence。
equal(reverse([1, 2, 3]), [3, 2, 1])
for i in reverse([1, 2, 3]) {
// 3, 2, 1
println(i)
}
startsWith(sequence1, sequence2)：如果序列sequence1中開頭的元素跟序列sequence2中的所有元素都相等，則返回true，否則返回false。
startsWith("foobar", "foo") == true
startsWith(10..100, 10..15) == true
var languages = ["Swift", "Objective-C"]
startsWith(languages, ["Swift"]) == true
上面提到的函數(shù)是我認(rèn)為在Swift編程中會(huì)經(jīng)常用到的函數(shù)。
完整74個(gè)內(nèi)置函數(shù)：
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(...)
