How do I sort an array of structs by multiple values?

sorting, swift

Solution

I'm not yet proficient in Swift, but the basic idea for a multiple-criteria sort is:

let sorted = conditions.sorted { (lhs: Condition, rhs: Condition) -> Bool in
    if lhs.set == rhs.set {
        return lhs.someString < rhs.someString
    }
    return (lhs.set) < (rhs.set)
}

Problem

I already have code to sort by 1 value as shown below, but I'm wondering how to sort using multiple values? I would like to sort by set and then by someString. One is an integer, and one is a string in this case. I had considered converting the integer to a string and then concatenating them, but thought there must be a better way because I may have 2 integers to sort by in the future. ``` struct Condition { var set = 0 var someString = "" } var conditions = [Condition]() conditions.append(Condition(set: 1, someString: "string3")) conditions.append(Condition(set: 2, someString: "string2")) conditions.append(Condition(set: 3, someString: "string7")) conditions.append(Condition(set: 1, someString: "string9")) conditions.append(Condition(set: 2, someString: "string4")) conditions.append(Condition(set: 3, someString: "string0")) conditions.append(Condition(set: 1, someString: "string1")) conditions.append(Condition(set: 2, someString: "string6")) // sort let sorted = conditions.sorted { (lhs: Condition, rhs: Condition) -> Bool in return (lhs.set) < (rhs.set) } // printed sorted conditions for index in 0...conditions.count-1 { println("\(sorted[index].set) - \(sorted[index].someString)") } ```

Original source