swift 截取字符串

swift3.0 使用String.Index來作位置索引，要想實現截取功能首先得獲取到String.Index;

獲取中間部分參數用Range<Index>便可；

let str:String = btn.currentTitle ?? ""

         let indes = str.index(str.startIndex, offsetBy: str.length - 1)

         let prefix = str.substring(to: indes)

         btn.setTitle(prefix + "▾", for: .normal)

舉例從開始截取到倒數第二位。

let index = str.index(str.endIndex, offsetBy: -5)
        
    let suffix = str.substring(from: index)

截取倒數五位

2.富文本設置 （空格也會佔位）

      guard let mingzi = model.name,let jieshao = model.bio else {

         return

      }

      let amountString = NSMutableAttributedString(string:"\(mingzi)／\(jieshao)")

      //設置字體顏色

      amountString.addAttribute(NSForegroundColorAttributeName, value: UIColor.black,range: NSMakeRange(0, "\(mingzi)".length + 1))

      amountString.addAttribute(NSFontAttributeName, value: UIFont.systemFont(ofSize: 13),range: NSMakeRange(0, "\(mingzi)".length + 1))

      

      amountString.addAttribute(NSForegroundColorAttributeName, value: UIColor.gray,range: NSMakeRange(1 + "\(mingzi)".length, "\(jieshao)".length))

      amountString.addAttribute(NSFontAttributeName, value: UIFont.systemFont(ofSize: 13),range: NSMakeRange(1 + "\(mingzi)".length, "\(jieshao)".length))

      self.bio.attributedText = amountString