How to Correctly Print Block Parameter in Swift?

Question

I see the following discrepancy in Playgrounds for Swift 1.2 and 2.0 when I want to print the value of a parameter in a block I am passing as input to a function. Any help in understanding what is going on would be appreciated!

func blockSample(myInput: String, myOutput: (answer: String) -> ()) {
    myOutput(answer: myInput)
}

blockSample("testthis") { (answer) -> () in
    print(answer) // This should print "testthis" but it doesn't
}

blockSample("testthis") { (answer) -> () in
    print("test") // print something before the next line
    print(answer) // this works. prints "testthis"
}

blockSample("testthis") { (answer) -> () in
    let printedAnswer = answer
    print(answer) // this works. prints "testthis". Note that I am printing answer and not printedAnswer
}

Answer 1

Your first example indeed doesn't print in the live panel of the Playground contrary to the others.

But with Xcode 7 Playgrounds if you open the menu:

View / Debug Area / Show Debug Area

you will see in the console that everything is printed properly.

In Xcode 6 Playgrounds you can achieve the same by displaying the Assistant Editor:

View / Assistant Editor / Show Assistant Editor

Also, remember that in Playgrounds you can force the display of a value in the live panel by just stating your variable on a separate line:

blockSample("testthis") { (answer) -> () in
    answer  //  this will force the live display of the value for 'answer'
    print(answer)
}