不推荐使用“substring(to:)":请使用带有“partial range upto"运算符的字符串切片下标 [英] 'substring(to:)' is deprecated: Please use String slicing subscript with a 'partial range upto' operator

问题描述

如何将以下代码更新到新版本的 swift:

How can I update the following code to the new version of swift:

self.areaCodeLael.text! = localNumber.substring(to: localNumber.index(localNumber.startIndex, offsetBy: 3))

我试过关注这篇文章，但我做对了如何在 Swift 4 中使用字符串切片下标?

I have tried following this post but I can't get it right How can I use String slicing subscripts in Swift 4?

我将原始代码调整为 localNumber[..<3] 但我得到:

I adjusted my original code to localNumber[..<3] but I get:

不能使用类型为PartialRangeUpTo"的索引为String"类型的值添加下标

Cannot subscript a value of type 'String' with an index of type 'PartialRangeUpTo'

推荐答案

在这种情况下我会说 localNumber.prefix(3).简短而甜蜜.

I would say localNumber.prefix(3) in this situation. Short and sweet.

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