vialyx

let admins = [User(name: "Admin")]
// [{name "Admin"}]
let guests = [User(name: "Guest")]
// [{name "Guest"}]

var allUsers = admins + guests
// [{name "Admin"}, {name "Guest"}]

// TODO: - Iterate over the entire collection with the for-in loop:
for user in allUsers {

vialyx

for (index, user) in allUsers.enumerated() {
    print("User: \(user) at index: \(index)")
    /*
     User: User(name: "Admin") at index: 0
     User: User(name: "Guest") at index: 1
     */
}

vialyx

// MARK: - Comparable
extension User: Comparable {
    
    static func <(lhs: User, rhs: User) -> Bool {
        return lhs.name < rhs.name
    }
    
    static func ==(lhs: User, rhs: User) -> Bool {
        return lhs.name == rhs.name
    }

vialyx

let incommingMessages: [String] = []
print("emptiness: \(incommingMessages.isEmpty)")
print("counting: \(incommingMessages.count == 0)")

vialyx

let messageIDs = Array<Int>(1...1000000)
let contiguousMessageIDs = ContiguousArray<Int>(1...1000000)

var start = CFAbsoluteTimeGetCurrent()
messageIDs.reduce(0, +)
var end = CFAbsoluteTimeGetCurrent() - start
print("Array reduce Took \(end) seconds")
// "Array reduce Took 0.203467965126038 seconds\n"

start = CFAbsoluteTimeGetCurrent()

vialyx

struct User {
    let id: Int
    let name: String
}

var users: Set<User> = []
// error: type 'User' does not confirm to protocol 'Hashable'

vialyx

struct User {
    let id: Int
    let name: String
}

extension User: Hashable {

    var hashValue: Int {
        return id
    }

vialyx

var users: Set<User> = []

let user = User(id: 65, name: "Maxim Vialyx")

users.insert(user)
// (inserted true, {id 65, name "Maxim Vialyx"})
users.insert(user)
// (inserted false, {id 65, name "Maxim Vialyx"})
users.remove(user)
// Return removed user and Set now is empty Set([])

vialyx

// TODO: - Use .isEmpty instead of .count
if allUsers.isEmpty {
    print("User list is empty")
} else {
    let user = allUsers.first
    // NOT subscript. Set is unordered collection
    // user = allUsers[0]
    print("First user is: \(user)")
    // "First user is: Optional(__lldb_expr_209.User(id: 654, name: "Chilly Mango"))\n"
}

vialyx

// TODO: - Iterate over the entire with the for-in loop:
for user in allUsers {
    print("User: \(user)")
    /*
     User: User(id: 654, name: "Chilly Mango")
     User: User(id: 7, name: "Mike Biggles")
     User: User(id: 234, name: "Midum Premium")
     User: User(id: 99, name: "Jimmy Cho")
     */
}