CODEWITHSUNDEEP
iosswiftcocoa-touchboolean
udbhateja
udbhateja

Reputation: 978

Swift's way to handle this situation instead of using bools

I have a function that I want only to execute if not executing currently. I have used a bool variable to check the current execution.

Is there any other solution provided by Swift to handle this instead of using Bool?

 guard
        !isExecuting,
        let currentNavVC = tabBarController.selectedViewController as? UINavigationController
        else { return }
    
    isExecuting = true
    
    let first = currentNavVC.viewControllers.first,
    let last = currentNavVC.viewControllers.last
    var controllers = [first]
    if first != last {
        controllers = [first, last]
    }
    
    DispatchQueue.main.async {
        currentNavVC.viewControllers = controllers
        isExecuting = false
    }

Bool variable: isExecuting

Note:

Tried using Semaphores(DispatchSemaphore) but they are of no help.
Also I am calling the above function in didReceiveMemoryWarning()

Any help will be appreciated and thanks in advance!!

Upvotes: 0

Views: 166

Answers (2)

Xuan-Gieng Nguyen
Xuan-Gieng Nguyen

Reputation: 846

I believe you also can use Operation with OperationQueue in this case.

Operation supports cancellation as well as checking if it is executing.

Ref:

OperationQueue: https://developer.apple.com/documentation/foundation/operationqueue

Operation: https://developer.apple.com/documentation/foundation/operation

Upvotes: 1

matt
matt

Reputation: 535138

I have a function that I want only to execute if not executing currently

You're looking for a lock. But locks of themselves are tricky and dangerous. The easy, safe way to get a lock is to use a serial queue. As we say, a serial queue is a form of lock. So:

  • If your function is called on the main queue, then it cannot execute if it is executing currently, and there is nothing to do. The main queue is a serial queue and there can be Only One.

  • If your function is called on a background queue, then make sure that your queue is a serial queue. For example, if you create your own DispatchQueue, it is serial by default.

Upvotes: 4

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