continue.swift

// MARK: Continue, break, throw

let numbers: [Int] = [1, 2, 3, 4, 5, 10, 11, 20]

// MARK: continue
var evenSum = 0
for number in numbers {
    if number % 2 != 0 { continue }
    
    evenSum += number
}
/*
 Calculate sum of even numbers.
 Skip not even numbers using 'continue' keyword.
 */

print("even summ: \(evenSum)")

// MARK: - break
var position = 0
let findNumber = 10
for (index, number) in numbers.enumerated() {
    if number == findNumber {
        position = index
        break
    }
}
/*
 Find number position in array.
 Stop loop using 'break' keyword when number has been found.
 */

print("number position: \(position)")

// MARK: return

enum MachingError: Error {
    case NotEnoughtCharacters(count: Int)
}

enum CollectionError: Error {
    case Empty
}

func joinKeys(lhs: String, rhs: String) throws -> String {
    let minCount = 5
    if lhs.isEmpty || rhs.isEmpty { throw CollectionError.Empty }
    if lhs.count < minCount || rhs.count < minCount { throw MachingError.NotEnoughtCharacters(count: minCount) }
    
    return lhs + rhs
}

do {
    try joinKeys(lhs: "", rhs: "")
} catch is CollectionError {
    print("empty")
} catch MachingError.NotEnoughtCharacters(let count) {
    print("maching error min count: \(count)")
}
/*
 That is better way than return nil value.
 - Throwing works faster
 - That is clear to understand when you receive CollectionError instead of nil result
 */