Swift的74标准功能
Swift中共同拥有74个内建函数,可是在Swift官方文档(“The
Swift Programming Language”)中仅仅记录了7中。剩下的67个都没有记录。
本文将列举Swift全部的内建函数。本文中提到的所谓的内建函数是指那些在Swift中不须要导入不论什么模块(如Foundation等)或者引用不论什么类就能够使用的函数。
abs(signedNumber): 返回给定的有符号数字的绝对值。
非常easy。可是没有在文档中记录。
- abs(-1) == 1
- abs(-42) == 42
- abs(42) == 42
contains(sequence, element): 假设给定的序列(如数组)包括特定的元素,则返回true。
- var languages = ["Swift", "Objective-C"]
- contains(languages, "Swift") == true
- contains(languages, "Java") == false
- contains([29, 85, 42, 96, 75], 42) == true
dropFirst(sequence): 返回一个去掉第一个元素的新序列(如数组)。
- var languages = ["Swift", "Objective-C"]
- var oldLanguages = dropFirst(languages)
- equal(oldLanguages, ["Objective-C"]) == true
dropLast(sequence): 返回一个的新序列(如数组),该序列去掉作为參数传递给函数的最后一个元素。
- var languages = ["Swift", "Objective-C"]
- var newLanguages = dropLast(languages)
- equal(newLanguages, ["Swift"]) == true
dump(object): 一个对象的内容转储到标准输出。
- var languages = ["Swift", "Objective-C"]
- dump(languages)
- // Prints:
- // ?
2 elements
- // - [0]: Swift
- // - [1]: Objective-C
equal(sequence1, sequence2): 假设序列1和序列2包括同样的元素,则返回true。
- var languages = ["Swift", "Objective-C"]
- equal(languages, ["Swift", "Objective-C"]) == true
- var oldLanguages = dropFirst(languages)
- equal(oldLanguages, ["Objective-C"]) == true
filter(sequence, includeElementClosure): 返回序列的一个元素,这个元素满足includeElementClosure所指定的条件。
- 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): 再给定的序列中返回一个指定的索引,假设在序列中没有找到这个元素就返回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): 在指定的序列中返回元素的索引(零索引)。
- equal(indices([29, 85, 42]), [0, 1, 2])
- for i in indices([29, 85, 42]) {
- // 0, 1, 2
- println(i)
- }
join(separator, sequence): 返回一个由给定的分隔符分离出来的序列的元素。
- join(":", ["A", "B", "C"]) == "A:B:C"
- var languages = ["Swift", "Objective-C"]
- join("/", languages) == "Swift/Objective-C"
map(sequence, transformClosure): 假设transformClosure适用于所给序列中全部的元素,则返回一个新序列。
- 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.): 返回函数所给參数中的最大值。
- max(0, 1) == 1
- max(8, 2, 3) == 8
maxElement(sequence): 返回所给序列的同类元素中的最大元素。
- maxElement(1...10) == 10
- var languages = ["Swift", "Objective-C"]
- maxElement(languages) == "Swift"
minElements(sequence): 返回所给序列的同类元素中的最小元素。
- minElement(1...10) == 1
- var languages = ["Swift", "Objective-C"]
- minElement(languages) == "Objective-C"
reduce(sequence, initial, combineClosure): 从第一个初始值開始对其进行combineClosure操作,递归式地将序列中的元素合并为一个元素。
- var languages = ["Swift", "Objective-C"]
- reduce(languages, "", { $0 + $1 }) == "SwiftObjective-C"
- reduce([10, 20, 5], 1, { $0 * $1 }) == 1000
reverse(sequence): 返回所给序列的倒序。
- equal(reverse([1, 2, 3]), [3, 2, 1])
- for i in reverse([1, 2, 3]) {
- // 3, 2, 1
- println(i)
- }
startsWith(sequence1, sequence2):假设序列1和序列2的起始元素相等,则返回true。
- startsWith("foobar", "foo") == true
- startsWith(10..100, 10..15) == true
- var languages = ["Swift", "Objective-C"]
- startsWith(languages, ["Swift"]) == true
例如以下列表为Swift中的74个内建函数。上文所描写叙述的函数是我觉得在日常开发中比較实用处的。当然我可能遗漏了一些经常使用函数。欢迎大家在评论中讨论,而且请用一个简短的代码段来展示怎样使用该函数。
- 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(...)