ios - 我想切换时间洗涤器以 15 分钟为间隔

Question

请建议我每隔 15 分钟去一次。例如:4:00、4:15、4:30、4:45 等等。

 @IBAction func sliderMoved(sender: UISlider) {

       let slot = Double(sender.value)
       let slotDate = self.timeFromSlot(slot)

       print(timeFormatter.stringFromDate(slotDate!))
    }

    private func timeFromSlot(slot:Double) -> NSDate? {

        let cal = NSCalendar.currentCalendar()
        let unit:NSCalendarUnit = [.Year, .Month, .Day, .Hour, .Minute, .Second]
        let comps = cal.components(unit, fromDate: NSDate())
        comps.hour = Int((slot % (24 * 3600)) / 3600)
        comps.minute = Int(slot % 3600 / 60)
        comps.second = 0

        let startedDate = cal.dateFromComponents(comps)!

        return startedDate
    }

我有 sliderMoved，起点是上午 8:00，终点是晚上 9:00 我设置了 slider 最小值 28,800 和最大值 75,600，当我滑动 slider 时，值随着我的 timeFromSlot 方法和更改后的值而变化我在 8:01 8:02 8:03 之间到达。我想像这样更改值 8:00 8:15 8:30。

Answer 1

对于您的情况，最好使用一些部分缩放。尝试下面的代码。我相信这非常简单。

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var slider: UISlider!
    @IBOutlet weak var label: UILabel!

    let ticksCount: Float = 13*4 // 15mins intervals count from 8am till 9pm
    let calendar = NSCalendar.currentCalendar()
    let todayDate = NSDate()

    override func viewDidLoad() {
        super.viewDidLoad()

        slider.minimumValue = 0
        slider.maximumValue = ticksCount
    }

    @IBAction func onValueChanged(slider: UISlider) {

        let minutesFromDayStart = 8 * 60 + Int(slider.value) * 15 // total minutes from day start, assuming we use intervals from 8am
        let timeSlotDate = dateWithTimeSlotForDate(todayDate, minutesFromDayStart: minutesFromDayStart)
        showDate(timeSlotDate)
    }

    private func showDate(date: NSDate) {
        let df = NSDateFormatter()
        df.dateStyle = .MediumStyle
        df.timeStyle = .MediumStyle

        label.text = df.stringFromDate(date)
    }

    private func dateWithTimeSlotForDate(date: NSDate, minutesFromDayStart: Int) -> NSDate {

        let dayStart = dayStartDateForDate(date)
        return calendar.dateByAddingUnit(.Minute, value: minutesFromDayStart, toDate: dayStart, options: NSCalendarOptions(rawValue: 0))!
    }

    private func dayStartDateForDate(date: NSDate) -> NSDate {
        return calendar.startOfDayForDate(date)
    }
}