小编Dan*_*oho的帖子

我正在尝试使用这些代码行

class Student {
    var name: String
    var age: Int?

    init(name: String) {
        self.name = name
    }

    func description() -> String {
        return age != nil ? "\(name) is \(age) years old." : "\(name) hides his age."
    }
}

var me = Student(name: "Daniel")
println(me.description())
me.age = 18
println(me.description())

上面的代码产生如下

Daniel hides his age.
Daniel is Optional(18) years old.

我的问题是为什么有可选(18)那里,我怎么能删除可选和只是打印

Daniel is 18 years old.

我从这里得到了代码jquery如何捕获输入键并将事件更改为选项卡

(function($) {
    $.fn.enterAsTab = function(options) {
        var settings = $.extend({
            'allowSubmit': false
        }, options);
        this.find('input, select, textarea, button').live("keypress", {localSettings: settings}, function(event) {
            if (settings.allowSubmit) {
                var type = $(this).attr("type");
                if (type == "submit") {
                    return true;
                }
            }
            if (event.keyCode == 13) {
                var inputs = $(this).parents("form").eq(0).find(":input:visible:not(disabled):not([readonly])");
                var idx = inputs.index(this);
                if (idx == inputs.length - 1) {
                    idx = -1;
                } else {
                    inputs[idx + 1].focus(); // handles submit buttons
                }
                try {
                    inputs[idx + 1].select();
                } …