斯威夫特4.0

string.capitalized(with: nil)

or

string.capitalized

但是，每个单词的首字母都要大写

苹果公司的文档:

A capitalized string is a string with the first character in each word changed to its corresponding uppercase value, and all remaining characters set to their corresponding lowercase values. A “word” is any sequence of characters delimited by spaces, tabs, or line terminators. Some common word delimiting punctuation isn’t considered, so this property may not generally produce the desired results for multiword strings. See the getLineStart(_:end:contentsEnd:for:) method for additional information.

我用柯尔斯泰因斯解得到了第一个复制的字符。这将大写第一个字符，不会看到双字符:

var s: String = "hello world"
s = prefix(s, 1).capitalizedString + suffix(s, countElements(s) - 1)

我不知道它的效率是高还是低，我只知道它给了我想要的结果。

Leonardo Savio Dabus:

我想大多数用例是获得适当的套管:

import Foundation

extension String {

    var toProper:String {
        var result = lowercaseString
        result.replaceRange(startIndex...startIndex, with: String(self[startIndex]).capitalizedString)
        return result
    }
}

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"

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"

斯威夫特4.0

string.capitalized(with: nil)

or

string.capitalized

但是，每个单词的首字母都要大写

苹果公司的文档:

A capitalized string is a string with the first character in each word changed to its corresponding uppercase value, and all remaining characters set to their corresponding lowercase values. A “word” is any sequence of characters delimited by spaces, tabs, or line terminators. Some common word delimiting punctuation isn’t considered, so this property may not generally produce the desired results for multiword strings. See the getLineStart(_:end:contentsEnd:for:) method for additional information.