CODEWITHSUNDEEP
iosswifthandleralertflurry
Mike K
Mike K

Reputation: 961

Swift - alert action handler error

I have some strange stuff going on: trying to track if a share action was cancelled in UIAlertAction handler with FLurry Analytics SDK. The code should basically look like that:

       let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel, handler: {
            (action:UIAlertAction!) -> Void in
            Flurry.logEvent("Share Cancelled")
            }
        )

But compiler shows an error "Extra argument "title" in call..." and highlights "Cancel" in red. Though if I add any variable declaration or simple function like println() than there is no error! i.e. this code is compiled correctly and considered to be working:

       let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel, handler: {
            (action:UIAlertAction!) -> Void in
            let somevar = 0
            Flurry.logEvent("Share Cancelled")
            }
        )

Have anyone faced a thing like that? Maybe it's a Swift or Flurry bug?

Upvotes: 2

Views: 1085

Answers (1)

Chris Conover
Chris Conover

Reputation: 9039

For sake of resolution, from my previous comment, Swift will try to infer the return type from a closure with a single statement. If you are trying to define a closure with a single statement that has a return value, then Swift will assume that to be the return value for your closure.

Since you noted that logEvent returns a value, you will need to explicitly return nothing at all, to create the proper closure.

For what it's worth, this appears to be changed / fixed in 6.3, as the following code now executes:

func foo() -> Int {
    return 1
}

func bar(() -> ()) {
    println("Hello from bar")
}

bar({ foo() })

In general, the way to debug ambiguous errors like this, is to break the statement into multiple lines, explicitly defining expected types at each stage, and watch where it breaks.

Upvotes: 0

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