swift 定时器的使用

参考：http://www.cnblogs.com/sxlfybb/p/3792611.html

NSTimer有2个构造函数

/*not inherited*/ init(timeInterval ti: NSTimeInterval, invocation: NSInvocation, repeats yesOrNo: Bool)
/*not inherited*/ init(timeInterval ti: NSTimeInterval, target aTarget: AnyObject, selector aSelector: Selector, userInfo: AnyObject?, repeats yesOrNo: Bool)

注意到，注释为未继承，所以 两个构造不能用

NSTimer有2个静态实例

    class func scheduledTimerWithTimeInterval(ti: NSTimeInterval, invocation: NSInvocation, repeats yesOrNo: Bool) -> NSTimer
    class func scheduledTimerWithTimeInterval(ti: NSTimeInterval, target aTarget: AnyObject, selector aSelector: Selector, userInfo: AnyObject?, repeats yesOrNo: Bool) -> NSTimer

在swift中，找不到 NSInvocation 类，日了狗了

还好有另一种使用静态函数的形式去实例化：

    func mNSTimer() {
        let timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: "timerFireMethod:", userInfo: "generalbenil", repeats: true)
        timer.fire() // 启动定时器
    }
    // 参数: The timer passes itself as the argument
    func timerFireMethod(timer: NSTimer) {
        print("\(timer.userInfo!)")
        let formatter = NSDateFormatter()
        formatter.dateFormat = "MM/dd/yyyy HH:mm:ss" // 这里注意时间的格式，大小写代表的意义不同！
        let strNow = formatter.stringFromDate(NSDate())
        print("the time is \(strNow)")

    }