Swift标准库函数

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1. abs 返回数字的绝对值

数轴上的点到原点的距离叫做绝对值

abs(Int32)

let number1 = abs(-12.4);

let number2 = abs(-12);

let number3 = abs(-13.0011 / 2);

// print result: 12.4, 12 ,6.50055

2. 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。

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

let isInclude1 = languages.contains("Swift");

let isInclude2 = languages.contains("Java");

// print result : true false

学自:http://letsswift.com/2014/06/74-swift-library-functions/