结合上面的答案，我写了一个小扩展，大写每个单词的第一个字母(因为这是我正在寻找的，并认为其他人可以使用它)。

我谦卑地提出:

extension String {
    var wordCaps:String {
        let listOfWords:[String] = self.componentsSeparatedByString(" ")
        var returnString: String = ""
        for word in listOfWords {
            if word != "" {
                var capWord = word.lowercaseString as String
                capWord.replaceRange(startIndex...startIndex, with: String(capWord[capWord.startIndex]).uppercaseString)
                returnString = returnString + capWord + " "
            }
        }
        if returnString.hasSuffix(" ") {
            returnString.removeAtIndex(returnString.endIndex.predecessor())
        }
        return returnString
    }
}

从Swift 3你可以很容易地使用 文本框。autocapitalizationType = uitextautocapitalizationtype .sentence

我假设您想要将整个单词串的第一个单词大写。例如:“我的猫很胖，我的脂肪很松弛”应该返回“我的猫很胖，我的脂肪很松弛”。

Swift 5:

为此，您可以导入Foundation，然后使用大写的属性。例子:

import Foundation
var x = "my cat is fat, and my fat is flabby"
print(x.capitalized)  //prints "My Cat Is Fat, And My Fat Is Flabby"

如果你想成为一个纯粹主义者，不导入基础，那么你可以创建一个字符串扩展。

extension String {
    func capitalize() -> String {
        let arr = self.split(separator: " ").map{String($0)}
        var result = [String]()
        for element in arr {
            result.append(String(element.uppercased().first ?? " ") + element.suffix(element.count-1))
        }
        return result.joined(separator: " ")
    }
}

然后你可以这样使用:

var x = "my cat is fat, and my fat is flabby"
print(x.capitalize()) //prints "My Cat Is Fat, And My Fat Is Flabby"

Swift 3 (xcode 8.3.3)

大写字符串的所有首字符

let str = "your string"
let capStr = str.capitalized

//Your String

全部大写

let str = "your string"
let upStr = str.uppercased()

//YOUR STRING

字符串的第一个字符只能大写

 var str = "your string"
 let capStr = String(str.characters.prefix(1)).uppercased() + String(str.characters.dropFirst())

//Your string

Swift 5.1或更高版本

extension StringProtocol {
    var firstUppercased: String { prefix(1).uppercased() + dropFirst() }
    var firstCapitalized: String { prefix(1).capitalized + dropFirst() }
}

斯威夫特5

extension StringProtocol {
    var firstUppercased: String { return prefix(1).uppercased() + dropFirst() }
    var firstCapitalized: String { return prefix(1).capitalized + dropFirst() }
}

"Swift".first  // "S"
"Swift".last   // "t"
"hello world!!!".firstUppercased  // "Hello world!!!"

"DŽ".firstCapitalized   // "Dž"
"Dž".firstCapitalized   // "Dž"
"dž".firstCapitalized   // "Dž"

如果你想大写字符串的每个字，你可以使用这个扩展

Swift 4 Xcode 9.2

extension String {
    var wordUppercased: String {
        var aryOfWord = self.split(separator: " ")
        aryOfWord =  aryOfWord.map({String($0.first!).uppercased() + $0.dropFirst()})
        return aryOfWord.joined(separator: " ")
    }
}

Used

print("simple text example".wordUppercased) //output:: "Simple Text Example"