删除字符串中的最后两个字符(Swift 3.0)

Question

有没有快速的方法来删除Swift 3.0中的字符串中的最后两个字符？我看到有一个简单的方法来删除最后一个字符作为明确指出这里.你知道如何删除最后两个字符吗？谢谢!

Answer 1

更新:Xcode 9•Swift 4或更高版本

现在String符合RangeReplaceableCollection,所以现在你可以直接在String中使用Array的方法dropLast,因此不再需要扩展.唯一的区别是它返回一个子串.如果你需要一个String,你需要从中初始化一个新的:

let string = "0123456789"
let substring1 = string.dropLast(2)         // "01234567"
let substring2 = substring1.dropLast()      // "0123456"
let result = String(substring2.dropLast())  // "012345"

Swift 3.x

您可以在字符上使用dropLast(n :)方法删除任意数量的字符:

extension LosslessStringConvertible {
    var string: String { .init(self) }
}

作为扩展:

let result = substring.dropLast().string

let string = "0123456789"
let substring1 = string.dropLast(2)         // "01234567"
let substring2 = substring1.dropLast()      // "0123456"
let result = String(substring2.dropLast())  // "012345"

Answer 2

var name: String = "Dolphin"
let endIndex = name.index(name.endIndex, offsetBy: -2)
let truncated = name.substring(to: endIndex)
print(name)      // "Dolphin"
print(truncated) // "Dolph"

Answer 3

迅捷4:

let str = "Hello, playground"
let newSTR1 = str.dropLast(3)
print(newSTR1) 

output: "Hello, playgro"

//---------------//

let str = "Hello, playground"
let newSTR2 = str.dropFirst(2)
print(newSTR2)

output: "llo, playground"