Can you list the standard built-in queue structures in programming languages?

In iOS (and generally in Swift and Objective-C), the following standard structures and mechanisms are used for working with queues:

• DispatchQueue (GCD - Grand Central Dispatch): Allows executing tasks asynchronously or synchronously in queues with different priorities. This is not a classic data queue, but a thread management mechanism.

• OperationQueue: A higher-level API for managing operations (subtasks), which uses queues and allows setting dependencies between operations.

• Array or LinkedList: For implementing custom queues, arrays or linked lists can be used.

• Swift Collections: The standard Swift library does not have a separate "Queue" structure, but a queue can be implemented based on an array using the append and removeFirst methods.

Example of a simple queue implementation in Swift:

struct Queue<T> {
    private var elements: [T] = []

    mutating func enqueue(_ value: T) {
        elements.append(value)
    }

    mutating func dequeue() -> T? {
        guard !elements.isEmpty else { return nil }
        return elements.removeFirst()
    }

    func peek() -> T? {
        return elements.first
    }
}

Thus, for task management in iOS, DispatchQueue and OperationQueue are most commonly used, and for data storage, a queue can be implemented manually.