有一個需求獲取當天的0點 做分界線, 然后去獲取步數(shù)的數(shù)據(jù)的, 發(fā)現(xiàn)都是oc的,

就轉(zhuǎn)了下swift版本的
`

extension NSDate{
/// 當前的0 點 0分 0 秒時間
var currentDayzeroOfDate:NSDate{

    let calendar:NSCalendar = NSCalendar.currentCalendar()
    //calendar.components(NSCalendarUnit(), fromDate: self)//UIntMax
    
    let unitFlags: NSCalendarUnit = [
        
        NSCalendarUnit.Year,
        NSCalendarUnit.Month,
        NSCalendarUnit.Day,
        .Hour,
        .Minute,
        .Second ]
    
    //calendar.components(unitFlags, fromDate: self)//解析當前的時間 返回NSDateComponents 解析后的數(shù)據(jù)后面設置解析后的時間在反轉(zhuǎn)
    let components = calendar.components(unitFlags, fromDate: self)//NSDateComponents() 不初始化, 直接返回解析的時間

    components.hour = 0
    components.minute = 0
    components.second = 0
    print(" 2  \(components.year)  \(components.month)  \(components.day) \( components.hour)")
    let date = calendar.dateFromComponents(components)

    return date!
}

}
`