杭州IOS培训
达内杭州IOS培训中心

TEL:0571-56020830

热门课程

Swift的74个常用内置函数

  • 时间:2016-02-15
  • 发布:杭州达内ios培训班_杭州达内ios培训_杭州ios培训
  • 来源:PHPERZ


    杭州达内IOS培训专家介绍一下Swift的74个常用内置函数,内置函数是指无需引入任何模块即可以直接使用的函数,非常实用,值得大家参考。

//断言,参数如果为`true`则继续,否则抛出异常

//assert mentioned on page 55

assert(true)

//计算序列的元素个数

// countElements mentioned on page 79

countElements("foo") == 3

//返回一个新的序列,其中每个元素是一个元组,

//第一个值为原来元素所在的位置`index`,第二个为原来序列中的元素

// enumerate mentioned on page 94

for (i, j) in enumerate(["A", "B"]) {

 // "0:A", "1:B" will be printed

println("\(i):\(j)")

}

//返回所有参数中的最小值

// min mentioned on page 246

min(8, 2, 3) == 2

//打印

// print mentioned on page 85

print("Hello ")

//打印(带换行)

// 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):返回数字的绝对值


abs(-1) == 1

abs(-42) == 42

abs(42) == 42


contains(sequence, element):如果某个序列sequence(比如说一个数组)包含指定的元素element,则返回true,否则返回false。


var languages = ["Swift", "Objective-C"]

contains(languages, "Swift") == true

contains(languages, "Java") == false

contains([29, 85, 42, 96, 75], 42) == true


dropFirst(sequence):返回一个去掉了首个元素的、新的序列(比如一个新数组)。


var languages = ["Swift", "Objective-C"]

var oldLanguages = dropFirst(languages)

equal(oldLanguages, ["Objective-C"]) == true


dropLast(sequence):返回一个去掉了最后一个元素的、新的序列(比如一个新数组)。


var languages = ["Swift", "Objective-C"]

var newLanguages = dropLast(languages)

equal(newLanguages, ["Swift"]) == true


dump(object):打印出某个对象object的所有信息


var languages = ["Swift", "Objective-C"]

dump(languages)

// Prints:

// ▿ 2 elements

// - [0]: Swift

// - [1]: Objective-C

 
equal(sequence1, sequence2):判断两个序列是否相等


var languages = ["Swift", "Objective-C"]

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

var oldLanguages = dropFirst(languages)

equal(oldLanguages, ["Objective-C"]) == true


filter(sequence, includeElementClosure):对序列sequence中每个元素都执行includeElementClosure闭包,并将所有闭包结果为true的元素合成一个新序列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,则返回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的复数)


equal(indices([29, 85, 42]), [0, 1, 2])

for i in indices([29, 85, 42]) {

 // 0, 1, 2

 println(i)

}


join(separator, sequence):将序列sequence通过分隔符separator连成一个字符串,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):对序列sequence中每个元素都执行includeElementClosure闭包,并将所有闭包的结果合成一个新序列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.):返回参数中的最大值。


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):给定一个序列sequence,以及一个初始值initial,然后将initial和序列里的第1个元素作为参数传入combineClosure中进行运算,得到的结果保存到initial;然后再将initial和第2个元素传入combineClosure中计算,结果保存到initial;重复计算直到所有sequence中的元素都计算完毕,并返回最终的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中开头的元素跟序列sequence2中的所有元素都相等,则返回true,否则返回false。


startsWith("foobar", "foo") == true

startsWith(10..100, 10..15) == true

var languages = ["Swift", "Objective-C"]

startsWith(languages, ["Swift"]) == true


    以上这些函数是达内IOS培训专家整理的,在Swift编程中会经常用到的函数。

    完整74个内置函数:


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(...)



上一篇:Swift与C语言指针结合的使用方法
下一篇:达内:入门ios语言要懂得哪些知识?

达内副总裁齐一楠接受新浪专访,解读2016达内耀升级

795万高校毕业生创历史,2017届毕业生就业近况几何?

达内Linux学员毕业2周就业率96%,薪资10000元

达内教育总裁韩少云受邀出席GIE国际教育峰会做主题演讲

选择城市和中心
贵州省

广西省

海南省