What is the maximum number of execution threads that can be run simultaneously at one time?

iOS does not have a strict limit on the number of threads that can be created, but in practice, the number of threads executing simultaneously is equal to the number of available processor cores. The operating system manages thread scheduling by switching them on the processor time.

It is important to understand that creating too many threads can lead to decreased performance due to the overhead of context switching.

For effective multithreading in iOS, it is recommended to use GCD (Grand Central Dispatch) or OperationQueue, which manage a thread pool and optimize their usage.