格式倒计时从总秒数到分秒数

Question

我的 swift 下面的代码让用户输入分钟数，然后在它输入时倒计时。但是，如果用户输入 12:00，它会从 720 开始倒计时。我希望它对其进行格式化以像 12:00、11:59 等那样进行倒计时。我所有的代码都没有情节提要。 Func timerAction 是所有这些发生的地方。

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {
let MAX_LENGTH_PHONENUMBER = 2
let ACCEPTABLE_NUMBERS     = "0123456789"
var enterTime = UITextField()
var lblTime = UILabel()
var startBTN = UIButton()
var timer = Timer()
var counter = 0

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.

    [enterTime,lblTime,startBTN].forEach{
        [=10=].backgroundColor = .systemRed
        view.addSubview([=10=])
        [=10=].translatesAutoresizingMaskIntoConstraints = false
    }

    enterTime.frame = CGRect(x: view.center.x-115, y: view.center.y-200, width: 60, height: 50)
    lblTime.frame = CGRect(x: view.center.x-115, y: view.center.y, width: 60, height: 50)
    startBTN.frame = CGRect(x: view.center.x-115, y: view.center.y+200, width: 60, height: 50)

    startBTN.addTarget(self, action: #selector(startHit), for: .touchDown)

    enterTime.placeholder = String("MM:SS")

    enterTime.delegate = self
    enterTime.addTarget(self, action: #selector(self.textFieldDidChange), for: UIControl.Event.editingChanged)
}



@objc func startHit() {
    timer.invalidate()
    counter = convertToSeconds(from: enterTime.text!)
    lblTime.text = String(counter)
    timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
}

@objc func timerAction() {
    counter -= 1
    lblTime.text = String(counter)
    if ( counter == 0 ) {
        timer.invalidate()
    }
}

func convertToSeconds(from timeString: String) -> Int {
    let components = timeString.components(separatedBy: ":")
    if components.count == 2 {
        let minutes = Int(components[0]) ?? 0
        let seconds = Int(components[1]) ?? 0
        return (minutes * 60) + seconds
    } else if components.count == 3 {
        let hours = Int(components[0]) ?? 0
        let minutes = Int(components[1]) ?? 0
        let seconds = Int(components[2]) ?? 0
        return (hours * 60 * 60) + (minutes * 60) + seconds
    } else {
        return 0
    }
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    let newLength: Int = textField.text!.count + string.count - range.length
    let numberOnly = NSCharacterSet.init(charactersIn: ACCEPTABLE_NUMBERS).inverted
    let strValid = string.rangeOfCharacter(from: numberOnly) == nil
    return (strValid && (newLength <= MAX_LENGTH_PHONENUMBER))
}



@objc func textFieldDidChange(_ textField: UITextField) {
    if  textField.text!.count == 2  {
        textField.text = textField.text! + ":00"
    }
}
}

Answer 1

现在，您只是将表示秒数的整数直接转换为字符串，在这两个地方：

@objc func startHit() {
    timer.invalidate()
    counter = convertToSeconds(from: enterTime.text!)
    lblTime.text = String(counter) <--------
    timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
}

@objc func timerAction() {
    counter -= 1
    lblTime.text = String(counter) <--------
    if ( counter == 0 ) {
        timer.invalidate()
    }
}

你需要改变这两个地方来使用更复杂的格式逻辑，将720之类的东西变成12:00：

@objc func startHit() {
    timer.invalidate()
    counter = convertToSeconds(from: enterTime.text!)
    lblTime.text = formatSeconds(counter)
    timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
}

@objc func timerAction() {
    counter -= 1
    lblTime.text = formatSeconds(counter)
    if ( counter == 0 ) {
        timer.invalidate()
    }
}

这里是 formatSeconds 的实现，它使用了 DateComponentsFormatter。这是一个格式化程序，非常适合像这样格式化时间量。

func formatSeconds(_ totalSeconds: Int) -> String {
    let formatter = DateComponentsFormatter()
    formatter.unitsStyle = .positional
    formatter.allowedUnits = [.minute, .second]
    formatter.zeroFormattingBehavior = .pad
    return formatter.string(from: TimeInterval(totalSeconds))!
}

格式倒计时从总秒数到分秒数

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