Thread safe access to a variable in a class

Question

in an application where there could be multiple threads running, and not sure about the possibilities if these methods will be accessed under a multhreaded environment or no

Answer 1

Here is another swift 3 solution which provides thread-safe access to AnyObject.

It allocates recursive pthread_mutex associated with 'object' if needed.

class LatencyManager
{
    private var latencies = [String : TimeInterval]()

    func set(hostName: String, latency: TimeInterval) {
        synchronizedBlock(lockedObject: latencies as AnyObject) { [weak self] in
            self?.latencies[hostName] = latency
        }
    }

    /// Provides thread-safe access to given object
    private func synchronizedBlock(lockedObject: AnyObject, block: () -> Void) {
        objc_sync_enter(lockedObject)
        block()
        objc_sync_exit(lockedObject)
    }
}

Then you can call for example set(hostName: "stackoverflow.com", latency: 1)

UPDATE

You can simply define a method in a swift file (not in a class):

/// Provides thread-safe access to given object
public func synchronizedAccess(to object: AnyObject, _ block: () -> Void)
{
    objc_sync_enter(object)
    block()
    objc_sync_exit(object)
}

And use it like this:

synchronizedAccess(to: myObject) {
    myObject.foo()
 }