CODEWITHSUNDEEP
iosswiftconcurrencygrand-central-dispatch
Russell Warwick
Russell Warwick

Reputation: 101

Dispatch Group not working for completion block

Trying to get return reply objects from a network call. The session is a class that is using the star scream API. I just can't seem to get this to work. It's only printing out 1 set of results which is the from the first id. What am I missing here?

let myGroup = DispatchGroup()

for i in 0 ..< marketIds.count {
    myGroup.enter()
    self.session.retrieve(withMethod: MarketKeys.key, withParameters: [MarketKeys.id: marketIds[i]], completion: { (results, error) in
        print("results \n")
        print(results!)
        myGroup.leave()
        })
    }
myGroup.notify(queue:.main) {
print("Done")
}

Upvotes: 4

Views: 3741

Answers (2)

Scriptable
Scriptable

Reputation: 19750

This article gives you a quick reference guide to simple DispatchGroup use.

An example:

let dispatchGroup = DispatchGroup()

dispatchGroup.enter()
longRunningFunction { dispatchGroup.leave() }

dispatchGroup.enter()
longRunningFunctionTwo { dispatchGroup.leave() }

dispatchGroup.notify(queue: .main) {
    print("Both functions complete 👍")
}

The notify function is called when all items in the queue have been processed and allows you to react to this accordingly. So the example above will run two long running tasks and then will output "Both functions complete 👍"

Upvotes: 5

Shehata Gamal
Shehata Gamal

Reputation: 100503

Add this so notification to group can be sent

 myGroup.notify(queue: .main) {
   print("Both functions complete 👍")
  }

Upvotes: 0

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