UITextField右對齊時剑肯，會有以下問題：
1.第一個字符輸入空格，光標會跳到左側观堂；
2.如果先輸入其它字符退子，然后輸入空格，此時輸入的空格不會立即顯示型将，直到再次輸入其它字符時該空格會與輸入的字符同時顯示出來寂祥；
3.輸入內容末尾是空格時，結束輸入后七兜，空格不展示丸凭，只在編輯的時候顯示

解決方案1：

private lazy var contentTextField: UITextField = {
        let textField = UITextField()
        textField.font = UIFont.normalFont()
        textField.textAlignment = .Right
        textField.delegate = self
        textField.addTarget(self, action: #selector(textChange(_:)), forControlEvents: .EditingChanged)
        return textField
}()

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
        if range.location == textField.text?.length && string == " " {
            textField.text = textField.text?.stringByAppendingString("\u{00a0}")
            // 調用一次textChange(textField)，解決攔截代理方法textField: shouldChangeCharactersInRange: replacementString:對于空格返回false時腕铸，不能監(jiān)聽UITextFieldTextDidChangeNotification的問題惜犀。
            textChange(textField)
            return false
        }
        return true
}

@objc private func textChange(textField : UITextField) {
        guard let text = textField.text else {
            return
        }
        // 使用時需要將空格替換回去
        if let callBack = callBackOfTextFieldEndEditing {
            let contentSpace = textField.text!.stringByReplacingOccurrencesOfString("\u{00a0}", withString: " ")
            let content = contentSpace.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
            callBack(text: content)
        }
}

解決方案2：

private lazy var contentTextField: UITextField = {
        let textField = UITextField()
        textField.font = UIFont.normalFont()
        textField.textAlignment = .Right
        textField.addTarget(self, action: #selector(textChange(_:)), forControlEvents: .EditingChanged)
        return textField
}()

@objc private func textChange(textField : UITextField) {
        guard let text = textField.text else {
            return
        }
        let range = textField.markedTextRange
        if range != nil {
            return
        }

        let textRange = textField.selectedTextRange
        textField.text = text.stringByReplacingOccurrencesOfString(" ", withString: "\u{00a0}")
        textField.selectedTextRange = textRange
        
        // 使用時需要將空格替換回去
        if let callBack = callBackOfTextFieldEndEditing {
            let contentSpace = textField.text!.stringByReplacingOccurrencesOfString("\u{00a0}", withString: " ")
            let content = contentSpace.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
            callBack(text: content)
        }
    }