我如何从字符串变量使用Swift删除最后一个字符?在文档中找不到。

下面是完整的例子:

var expression = "45+22"
expression = expression.substringToIndex(countElements(expression) - 1)

当前回答

全局的dropLast()函数作用于序列,因此也作用于字符串:

var expression  = "45+22"
expression = dropLast(expression)  // "45+2"

// in Swift 2.0 (according to cromanelli's comment below)
expression = String(expression.characters.dropLast())

其他回答

修剪字符串最后一个字符最简单的方法是:

title = title[title.startIndex ..< title.endIndex.advancedBy(-1)]

全局的dropLast()函数作用于序列,因此也作用于字符串:

var expression  = "45+22"
expression = dropLast(expression)  // "45+2"

// in Swift 2.0 (according to cromanelli's comment below)
expression = String(expression.characters.dropLast())

使用新的Substring类型用法:

斯威夫特4:

var before: String = "Hello world!"
var lastCharIndex: Int = before.endIndex
var after:String = String(before[..<lastCharIndex])
print(after) // Hello world

短:

var before: String = "Hello world!"
after = String(before[..<before.endIndex])
print(after) // Hello world
let str = "abc"
let substr = str.substringToIndex(str.endIndex.predecessor())  // "ab"

斯威夫特4

var welcome = "Hello World!"
welcome = String(welcome[..<welcome.index(before:welcome.endIndex)])

or

welcome.remove(at: welcome.index(before: welcome.endIndex))

or

welcome = String(welcome.dropLast())