Can you explain what multithreading is in programming?

Multithreading is the ability of a program to execute multiple threads (execution paths) simultaneously. In iOS, this helps, for example, to avoid blocking the main thread (UI thread) when performing long operations, such as loading data from the network or processing large arrays.

Each thread operates independently but can share resources, which requires synchronization to prevent errors.

An example of using multithreading in iOS with GCD (Grand Central Dispatch):

DispatchQueue.global(qos: .background).async {
    // Long operation in the background thread
    let data = fetchDataFromNetwork()
    DispatchQueue.main.async {
        // Update UI on the main thread
        self.updateUI(with: data)
    }
}