swift 数组是否包含 查找数组元素 查找数组索引 查找最大元素和最小元素

contains(_:)判断是否包含给定元素

contains(where:)判断数组是否包含复合给定条件的元素

判断所有元素是否符合某个条件

allSatisfy(_:)判断数组的每一个元素都复合给定的条件

//: A UIKit based Playground for presenting user interface

import UIKit
var array = [Int](6..<20)
print(array.allSatisfy({$0>=5}))

print(array.allSatisfy({$0<5}))

true

false

查找元素

first 返回第一个元素（optional）如果数组为空 返回nil

last 返回数组最后一个元素 （optional） 如果数组为空，返回nil

first（while：）返回数组第一个复合给定条件的元素（optional）

last（while：）返回最后一个符合给定条件的元素（optional）

//: A UIKit based Playground for presenting user interface

import UIKit
var array = [10,231,3,123,123,12,312,3,121234,1]
print(array.first)
print(array.last)
print(array.first(where: { $0 > 10 }))
print(array.last(where: { $0 > 10 }))

结果

Optional(10)
Optional(1)
Optional(231)
Optional(121234)

查找数组索引

//: A UIKit based Playground for presenting user interface

import UIKit
var array = [10,231,3,123,123,10,12,312,3,121234,1]
print(array.firstIndex(of: 10))

print(array.lastIndex(of: 3))

Optional(0)
Optional(8)

同样的也适用于条件

//: A UIKit based Playground for presenting user interface

import UIKit
var array = [10,231,3,123,123,10,12,312,3,121234,1]
print(array.firstIndex(where: {$0 > 20}))

print(array.lastIndex(where: {$0 > 20}))

Optional(1)
Optional(9)

寻找最大元素和最小元素

//: A UIKit based Playground for presenting user interface

import UIKit
var array = [10,231,3,123,123,10,12,312,3,121234,1]
print(array.min())
print(array.max())

Optional(1)

Optional(121234)

对于元祖中的数组如何查找最大最小值呢

//: A UIKit based Playground for presenting user interface

import UIKit
var array = [(42,"erro2"),(41,"erro1"),(43,"erro3")]
print(array.min {a,b in a.0<b.0})
print(array.max {a,b in a.0<b.0})

Optional((41, "erro1"))

Optional((43, "erro3"))