IOS8 Trailing Closures in Swift

Question

let callActionHandler = { (action:UIAlertAction!) -> Void) in
        let alertMessage = UIAlertController(title: "Service Unavailable", message: "Sorry, the call feature is not available yet. Please retry later", preferredStyle: UIAlertControllerStyle.Alert)
        alertMessage.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alertMessage, animated: true, completion: nil)
    };    

// Code Snippet 1
let callAction = UIAlertAction(title: "Call" + "123-000-\(indexPath.row)", style: UIAlertActionStyle.Default ) { (action:UIAlertAction!) -> Void in
        println("check this out")
}

// Code Snippet 2
let callAction = UIAlertAction(title: "Call" + "123-000-\(indexPath.row)", style: UIAlertActionStyle.Default, handler: { (action:UIAlertAction!) -> Void in  
        println("Lets check this out")
})

// Code Snippet 3
let callAction = UIAlertAction(title: "Call" + "123-000-\(indexPath.row)", style: UIAlertActionStyle.Default , handler: callActionHandler)

• Here we have 3 code snippets, my doubts are:
  • What is the difference between Code Snippet 1 and Code Snippet 2?
  • Which of fragment 1 or fragment 2 is the best representation and should be used?
  • What exactly does Snippet 1 code mean? Is this a kind of property (completion) of observation in fast?
  • The way we want to write iOS8 is shown in Snippet 1, i.e. when I press the enter button during Xcode autocompletion, it converts to Snippet 1. Should we use Code Snippet 1 or still prefer to use Snippet 2/3, because they are easy to understand?

thank

Answer 1

You asked:

• What is the difference between Code Snippet 1 and Code Snippet 2?

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let callAction = UIAlertAction(title: "Call 123-000-\(indexPath.row)", style: .default) { action in
    print("check this out")
}