Swift intercept string (reprint)

Swift 3 String has three methods for string interception:

str.substring(to: String.Index)str.substring(from: String.Index)str.substring(with: Range<String.Index>)

Examples used to do the demonstration:

var str = "Hello, World"

Str.substring (To:String.Index)

This method intercepts the index specified by the parameter from the beginning of the string to .

let index = str.index(str.startIndex, offsetBy: 5)  //索引为从开始偏移5个位置str.substring(to: index)  // 获取Hello

SUBSTRING (from:String.Index)

This method intercepts the from end of the string from the index specified by the parameter.

let index = str.index(str.startIndex, offsetBy: 7) //索引从开始偏移7个位置str.substring(from: index)  // 输出World

Str.substring (with:range<string.index>)

This method intercepts the specified string range, which is specified by range. Similar to the Swift 2 String.substringWithRange .

let start = str.index(str.startIndex, offsetBy: 7)  //索引从开始偏移7个位置let end = str.index(str.endIndex, offsetBy: -3)   //所有从末尾往回偏移三个位置let range = start..<endstr.substring(with: range)  // 输出Wo

Swift intercept string (reprint)