Closures - Part I

/*
 CLOSURES - PART ONE
 */
// Closures are methods that are assigned to variables that can be called using that variable and even passed to other functions.
// They are functions without a name and are written differently than named functions

// BASIC CLOSURE
let driving1 = {
    print("I'm driving in my car")
}
driving1()   // Calling closure like regular function

// ACCEPTING PARAMETERS
// Parameters goes inside curly braces followed by "in"
// and placed before body of closure.
let driving2 = { (place: String) in
    print("I'm driving to \(place) in my car")
}
// When calling closure, parameter label isn't used:
driving2("Montreal")    // "I'm  driving to Montreal in my car"

// RETURNING VALUES
// Return type placed after parameters but before "in"
let driving3 = { (place: String) -> String in
    return "I'm driving to \(place) in my car"
}
let message = driving3("London")
print(message)

// CLOSURES AS PARAMETERS
// Return to basic closure that accepts no values
// and returns no value and would be expressed as:
// () -> Void
let driving4 = {
    print("I'm driving in my car")
}
// Create function that accepts closure as parameter:
func travel(action: () -> Void) {
    print("I'm getting ready to go.")
    action()
    print("I have arrived.")
}
// Call function with closure as parameter:
travel(action: driving4)

// TRAILING CLOSURE SYNTAX
// If the last parameter in a function is a closure,
// we can pass it directly after the function call.
travel() {
    print("I'm driving in my car")
}
// If the function accepts no other parameters,
// the () can be elminated.
travel {
    print("I'm driving in my car.")
}