我正在尝试制作一个自动更正系统，当用户输入一个大写字母的单词时，自动更正不起作用。为了解决这个问题，我复制了键入的字符串，应用了. lowercasestring，然后比较它们。如果字符串确实输入错误，则应该更正单词。然而，取而代之的单词都是小写的。所以我需要对第一个字母应用. uppercasestring。我本来觉得我可以用
nameOfString[0]
但这显然行不通。我怎么能得到字符串的第一个字母大写，然后能够打印完整的字符串与第一个字母大写?
谢谢你的帮助!
当前回答
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.
其他回答
下面是我一小步一小步完成的方法，类似于@Kirsteins。
func capitalizedPhrase(phrase:String) -> String {
let firstCharIndex = advance(phrase.startIndex, 1)
let firstChar = phrase.substringToIndex(firstCharIndex).uppercaseString
let firstCharRange = phrase.startIndex..<firstCharIndex
return phrase.stringByReplacingCharactersInRange(firstCharRange, withString: firstChar)
}
包括与API准则一致的突变和非突变版本。
斯威夫特3:
extension String {
func capitalizingFirstLetter() -> String {
let first = String(characters.prefix(1)).capitalized
let other = String(characters.dropFirst())
return first + other
}
mutating func capitalizeFirstLetter() {
self = self.capitalizingFirstLetter()
}
}
斯威夫特4:
extension String {
func capitalizingFirstLetter() -> String {
return prefix(1).uppercased() + self.lowercased().dropFirst()
}
mutating func capitalizeFirstLetter() {
self = self.capitalizingFirstLetter()
}
}
Swift 4 (Xcode 9.1)
extension String {
var capEachWord: String {
return self.split(separator: " ").map { word in
return String([word.startIndex]).uppercased() + word.lowercased().dropFirst()
}.joined(separator: " ")
}
}
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.
我的解决方案:
func firstCharacterUppercaseString(string: String) -> String {
var str = string as NSString
let firstUppercaseCharacter = str.substringToIndex(1).uppercaseString
let firstUppercaseCharacterString = str.stringByReplacingCharactersInRange(NSMakeRange(0, 1), withString: firstUppercaseCharacter)
return firstUppercaseCharacterString
}
