原由

因为需要做到金额的控制,最小金额是角,然后需要判断大于0.5元才可以开启留言功能,所以整理了下 string 的方法,希望能够帮助到需要的人.

开始

@IBOutlet weak var money: UITextField!
@IBOutlet weak var msg: UITextField!

msg.delegate = self
money.delegate = self
money.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: UIControlEvents.editingChanged)

func textFieldDidChange(textField:UITextField){
        if textField.text == "" {
            button.isEnabled = false
            return
        }
        let index = textField.text!.index(textField.text!.startIndex, offsetBy: 1)
        if textField.text?.substring(to: index) == "."{
            textField.text = ""
        }
        if ((textField.text?.range(of: ".")) != nil) {
            if (textField.text?.components(separatedBy: ".").count)! > 2 {
                textField.text?.remove(at: textField.text!.index(before: textField.text!.endIndex))
            }
            if (textField.text?.components(separatedBy: ".").count)! > 1 {
                let pos = textField.text?.characters.distance(from: textField.text!.startIndex, to: textField.text!.characters.index(of: ".")!)
                let str = textField.text?.substring(from: textField.text!.index(textField.text!.startIndex, offsetBy: pos!+1))
                if str?.characters.count==2{
                    textField.text?.remove(at: textField.text!.index(before: textField.text!.endIndex))
                }
            }
        }
        
        button.isEnabled = true
    }

func textFieldDidEndEditing(_ textField: UITextField) {
        if textField == money {
            if textField.text == "" {
                return
            }
            let index = textField.text!.index(textField.text!.startIndex, offsetBy: textField.text!.characters.count-1)
            if textField.text?.substring(from: index) == "."{
                textField.text?.append("0")
            }
            let cash = Float(textField.text!)!
            if cash >= 0.5 {
                msg.isEnabled = true
                msg.textColor = UIColor.black
            }else{
                msg.isEnabled = false
                msg.textColor = UIColor.lightGray
            }
        }
    }