如何在swift中比较阈值内的两个字符串值？

Question

I am trying to write a code where I have got two time[hh:min] data(String type). Need to just compare but the challenge is my code undergones some validations before returning the final values. so the assertion fails sometimes stating expected value is [17:04] but actual is [17:05]. Is there any way where we can use concept of Threshold that upto few minutes (say 2 mins) the comparison will still be valid?

Answer 1

Step one is do not store a thing as something that it is not. If these are times, they should be stored as times . Strings are for representation to the users; underlying storage is for reality.

So now let's store our times as date components:

let t1 = DateComponents(hour:17, minute:4)
let t2 = DateComponents(hour:17, minute:5)

Now it's easy to find out how far apart they are:

let cal = Calendar(identifier: .gregorian)
if let d1 = cal.date(from: t1),
    let d2 = cal.date(from: t2) {
        let diff = abs(d1.timeIntervalSince(d2))
        // and now decide what to do
}

Answer 2

You first need to seprate your string to an array, and then you can compare.

/* That two arrays are A1 and A2 */
let minute1 = Int(A1[0])*60+Int(A1[1])
let minute2 = Int(A2[0])*60+Int(A2[1])

This may help you. I think that @Sweeper did not understand that it is a time, not a date.

Answer 3

You can convert your string to minutes, subtract one from another and check if the absolute value is less than the threshold:

extension String {
    var time24hToMinutes: Int? {
        guard count == 5, let hours = Int(prefix(2)), let minutes = Int(suffix(2)), Array(self)[2] == ":"  else { return nil }
        return hours * 60 + minutes
    }
    func time24hCompare(to other: String, threshold: Int = 2) -> Bool {
        guard let lhs = time24hToMinutes, let rhs = other.time24hToMinutes else { return false }
        return abs(lhs-rhs) < threshold
    }
}

---

Testing:

"17:02".time24hCompare(to: "17:04")  // false
"17:03".time24hCompare(to: "17:04")  // true
"17:04".time24hCompare(to: "17:04")  // true
"17:05".time24hCompare(to: "17:04")  // true
"17:06".time24hCompare(to: "17:04")  // false