iOS intercepts specific strings (regular matches)

Sometimes we have a need to intercept other strings from a string, depending on the situation, we analyze several methods ~ ~

I. strings in fixed-length strings that intercept fixed-position lengths

// 这是比较简单的一种情况:比如截取手机号的后4位 let phoneNum = "18515383061" var suffixNum:String? // 从倒数第四位开始截取,截取到最后 suffixNum = phoneNum.substringFromIndex(phoneNum.endIndex.advancedBy(-4)) // 从开头截取到第三位,获取手机号前3位 let prefixNum = phoneNum.substringToIndex(phoneNum.startIndex.advancedBy(3)) // 截取区间内字符串 suffixNum = phoneNum.substringWithRange(phoneNum.endIndex.advancedBy(-4)..<phoneNum.endIndex)

two. non-fixed-length strings, but with delimiters

 //例如获取日期中的年,月,日 // 分割符可以是任意的字符,一般为‘/‘,‘_‘,‘空格‘,或者是特殊的字符. let timeStr = "2013/10/26" let timeArr = timeStr.componentsSeparatedByString("/") print(timeArr)

three. non-fixed-length string, take a string under special rules

 //As shown below, we want to intercept the string inside the first bracket//assuming that the string is returned by the server, the length of the variable, the position of the brackets is also uncertain, successively through a simple interception is more difficult// This is the time to use the * * Regular expression * *, I believe you know, but how to use the regular expression in Swift to filter the value, let us analyze//rangofstring is used to collect the string in the text, but you can choose the mode. Here choose (. Regularexpressionsearch) that is the regular search//But OC and Swift have only this method of receiving, only search, no other, compared to other languages (python,php) Weak too much// Simple match in parentheses in the word is presumably everyone will write "\\[.*\\", but there is a problem is that the content is ' [thing] jflsdfs [do] ', which is obviously not what we want//this will receive a regular greedy mode, by default it matches as many strings as required , and we want him to meet the most delicate that, we need to add a number, that is, "\\[.*?\\", so the search is ' [thing] '//You find that this is not what we want, why bring ' [' and '] ', but no way, this is your search conditions AH// But nothing is too hard to pour, the regular is 0 wide assertion,< 0 width positive lookahead assertion (? =exp) > Assert itself where the occurrence of the position behind can match the expression exp,//< 0 width is recalling after the assertion (? <=exp); It asserts that the front of the position itself appears to match the expression exp, and finally our expression is "(? <=\\[)." =\\]) "Let string =" I want to does some [thing] jflsdfs [do] "if let result = String.rangeofstring (" (? <=\\[). *? =\\]) ", Options:. Regularexpressionsearch, Range:string.startIndex. <string.endindex, Locale:nil) {print (String.substringwithrange (Result)}}  

Ssbun
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iOS intercepts specific strings (regular matches)