倒計(jì)時

原始版本

僅貼出計(jì)算時間的核心代碼

//每個時間間隔0.1s調(diào)用一次
func secondsToTimeString(seconds: Float) -> (String, Int, Int, Int, Int, Int) {
    
    let temp = seconds
    let seconds = Int(temp)
    
    // 天數(shù)計(jì)算
    let days = (seconds)/(24*3600);
    //小時計(jì)算
    let hours = (seconds)%(24*3600)/3600;
    //分鐘計(jì)算
    let minutes = (seconds)%3600/60;
    //秒計(jì)算
    let second = (seconds)%60;
    let timeString  = String(format: "%lu天 %02lu:%02lu:%02lu", days, hours, minutes, second)
    return (timeString, days, hours, minutes, second, Int((temp-Float(seconds))*10))
}

每次調(diào)用都需要重新計(jì)算時分秒喂击，計(jì)算很頻繁。CPU這樣也太累了吧？于是我決定給它減減負(fù)夯辖。實(shí)際上大多數(shù)時間有些數(shù)字都不會變動。比如分鐘60秒才會變一次董饰，小時60分鐘才會變一次蒿褂。等等。

進(jìn)化版本

定義如下屬性：
var days: Int?;

//小時
var hours: Int?;
var hoursFlag: Bool = false

//分鐘
var minutes: Int?
var minutesFlag: Bool = false

//秒
var second: Int?;
var secondFlag: Bool = false

//每個時間間隔0.1s調(diào)用一次
func secondsToTimeString2(seconds: Float) -> (Int, Int, Int, Int, Int) {
    let temp = seconds
    let seconds = Int(temp)
    let minInterval = Int((temp-Float(seconds))*10)
    if second == nil {
        second = (seconds)%60
    }
    if minutes == nil {
        minutes = (seconds)%3600/60
    }
    if hours == nil {
        hours = (seconds)%(24*3600)/3600
    }
    if days == nil {
        days = (seconds)/(24*3600)
        return (days!, hours!, minutes!, second!, minInterval)
    }
    if minInterval == 9  {
        secondFlag = true
        if second == 0 {
            second = 60
            second! -= 1
        } else {
            second! -= 1
        }
    }
    if second == 59 && secondFlag == true {
        secondFlag = false
        minutesFlag = true
        if minutes == 0 {
            minutes = 60
            minutes! -= 1
        } else {
            minutes! -= 1
        }
    }
    if minutes == 59 && minutesFlag == true {
        minutesFlag = false
        hoursFlag = true
        if hours == 0 {
            hours = 24
            hours! -= 1
        } else {
            hours! -= 1
        }
    }
    if hours == 23 && hoursFlag == true {
        hoursFlag = false
        if days != 0 {
            days! -= 1
        }
    }
    return (days!, hours!, minutes!, second!, minInterval)
}

代碼變得復(fù)雜多了卒暂，你們覺得我是不是咸的蛋疼啄栓？哈哈哈，我就是這樣追求極致的呀也祠！
代碼雖然多了很多昙楚，也花了我不少時間debug。但是改進(jìn)后性能卻提升了很多诈嘿。