Swift: Return boolean in GCD Completion Block

问题

I have a function written in Swift. I want the completion block to return a boolean. How can I go about doing this? I am using Grand Central Dispatch.

func myFunc() -> Bool 
{
    var success:Bool = false 

    // code here 

    dispatch_async(dispatch_get_main_queue(), { 
        return success
        )}
    )}
}

thanks!

回答1:

Standard why of dealing with this async nature is not to return value, but pass in completion handler:

func myFunc(completion:(success: Bool) -> ()) {
    var success:Bool = false

    // code here

    dispatch_async(dispatch_get_main_queue()) {
        completion(success: success)
    }
}

Then work with it:

myFunc({ (success) in
    // ...
})

来源：https://stackoverflow.com/questions/26847344/swift-return-boolean-in-gcd-completion-block