用小写字母替换部分字符串 - Swift

Question

我有一个基于 Swift 的 iOS 应用程序，其中一个功能允许您对 post 发表评论。无论如何，用户可以在他们的 post 中添加“@mentions”来标记其他人。但是我想阻止用户添加带有大写字母的用户名。

有没有办法转换一个字符串，让@usernames 全部变成小写？

例如：

I really enjoy sightseeing with @uSerABC (not allowed)

I really enjoy sightseeing with @userabc (allowed)

我知道 swift 中的字符串有一个属性称为 .lowercaseString - 但问题是它使整个字符串小写，这不是我想要的想。我只希望@username 小写。

有什么办法可以解决这个问题，必须使用 .lowercase 属性.

丹，谢谢你的时间。

Answer 1

这来自我用来检测主题标签的代码，我已经修改以检测提及：

func detectMentionsInText(text: String) -> [NSRange]? {
        let mentionsDetector = try? NSRegularExpression(pattern: "@(\w+)", options: NSRegularExpressionOptions.CaseInsensitive)
        let results = mentionsDetector?.matchesInString(text, options: NSMatchingOptions.WithoutAnchoringBounds, range: NSMakeRange(0, text.utf16.count)).map { [=10=] }
        return results?.map{[=10=].rangeAtIndex(0)}
    }

它通过使用正则表达式和 returns NSRange 数组来检测字符串中的所有提及项，通过使用范围，您可以得到 "mention" 的开头和结尾，您可以轻松替换他们用小写版本。

Answer 2

使用以下命令将字符串分成两部分 -

let arr = myString.componentsSeparatedByString("@")
//Convert arr[1] to lower case  
//Append to arr[0]
//Enjoy

Answer 3

感谢大家的帮助。最后我无法得到任何解决方案，经过大量测试，我想出了这个解决方案：

func correctStringWithUsernames(inputString: String, completion: (correctString: String) -> Void) {

            // Create the final string and get all
            // the seperate strings from the data.
            var finalString: String!
            var commentSegments: NSArray!
            commentSegments = inputString.componentsSeparatedByString(" ")

            if (commentSegments.count > 0) {

                for (var loop = 0; loop < commentSegments.count; loop++) {

                    // Check the username to ensure that there
                    // are no capital letters in the string.
                    let currentString = commentSegments[loop] as! String
                    let capitalLetterRegEx  = ".*[A-Z]+.*"
                    let textData = NSPredicate(format:"SELF MATCHES %@", capitalLetterRegEx)
                    let capitalResult = textData.evaluateWithObject(currentString)

                    // Check if the current loop string
                    // is a @user mention string or not.

                    if (currentString.containsString("@")) {

                        // If we are in the first loop then set the
                        // string otherwise concatenate the string.

                        if (loop == 0) {

                            if (capitalResult == true) {

                                // The username contains capital letters
                                // so change it to a lower case version.
                                finalString = currentString.lowercaseString
                            }

                            else {

                                // The username does not contain capital letters.
                                finalString = currentString
                            }
                        }

                        else {

                            if (capitalResult == true) {

                                // The username contains capital letters
                                // so change it to a lower case version.
                                finalString = "\(finalString) \(currentString.lowercaseString)"
                            }

                            else {

                                // The username does not contain capital letters.
                                finalString = "\(finalString) \(currentString)"
                            }
                        }
                    }

                    else {

                        // The current string is NOT a @user mention
                        // so simply set or concatenate the finalString.

                        if (loop == 0) {
                            finalString = currentString
                        }

                        else {
                            finalString = "\(finalString) \(currentString)"
                        }
                    }
                }
            }

            else {

                // No issues pass back the string.
                finalString = inputString
            }

            // Pass back the correct username string.
            completion(correctString: finalString)       
}

它当然不是最优雅或最有效的解决方案，但它确实有效。如果有任何改进的方法，请发表评论。

用小写字母替换部分字符串 - Swift

Replace part of string with lower case letters - Swift

ios

string

swift

var

lowercase