How does the use of synchronous and sequential methods differ in programming?

Synchronous methods are executed sequentially and block the current thread until they complete. This means that the program waits for the operation to finish before moving on to the next step.

Sequential methods are simply methods that are called one after another in a specific order. They can be either synchronous or asynchronous, but the call sequence guarantees that the next method will not start before the previous one is called.

In iOS, for example, a synchronous network request call will block the main thread, leading to a frozen interface. Therefore, asynchronous methods are often used, which do not block the thread, allowing other tasks to run in parallel.

Example of a synchronous call:

let data = try? Data(contentsOf: url) // Blocks the thread until the data is loaded

Example of a sequential (asynchronous) call:

fetchData { data in
    processData(data) // Executes after data is received
}

In summary, synchronous methods block the thread, while sequential methods refer to the order of calls, which can be either synchronous or asynchronous.