简单回答(2015-04-16有效):removeAtIndex(mystring . endindex .前任())

例子:

var howToBeHappy = "Practice compassion, attention and gratitude. And smile!!"
howToBeHappy.removeAtIndex(howToBeHappy.endIndex.predecessor())
println(howToBeHappy)
// "Practice compassion, attention and gratitude. And smile!"

元:

语言继续着它的快速进化，使得许多以前很好的sos答案的半衰期变得危险地短暂。学习语言并参考真正的文档总是最好的。

另一种方法如果你想从末尾删除一个或多个字符。

var myStr = "Hello World!"
myStr = (myStr as NSString).substringToIndex((myStr as NSString).length-XX)

其中XX是要删除的字符数。

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

斯威夫特4.2

我还删除了我的最后一个字符从字符串(即UILabel文本)在IOS应用程序

@IBOutlet weak var labelText: UILabel! // Do Connection with UILabel

@IBAction func whenXButtonPress(_ sender: UIButton) { // Do Connection With X Button

    labelText.text = String((labelText.text?.dropLast())!) // Delete the last caracter and assign it

}

使用函数removeAtIndex(i: String.Index)

var s = "abc"    
s.removeAtIndex(s.endIndex.predecessor())  // "ab"

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())