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iOS

Posted by tmsmth
tmsmth
10,543 Points

using guard

In the helper method video for the story app, Pasan wrote :

guard firstChoice != nil && secondChoice != nil else { return page }

For me, this means that if one of two is nil or both are nil then return page but if both are not nil then don't go to the else clause.

But in the video, Pasan uses this saying 'if both are not nil then return page' so i'm confused !

Taylor Smith
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Taylor Smith
iOS Development Techdegree Graduate 14,153 Points
Taylor Smith
.a{fill-rule:evenodd;}techdegree seal-36
Taylor Smith
iOS Development Techdegree Graduate 14,153 Points

I don't remember the video all that well, but it sounds like the code should look like this:

guard firstChoice != nil && secondChoice != nil else {

// do something here if one or both ARE nil }

return page

maybe "return page" was not suppose to be in the else brackets

tmsmth
tmsmth
10,543 Points

Would make more sens, thanks !

1 Answer

Jhoan Arango
Jhoan Arango
14,575 Points
Jhoan Arango
Jhoan Arango
14,575 Points

Hello,

The guard statement is for an early exit. "You use the guard statement to require that a condition must be true in order for the code after the guard statement to be executed."

So in your example, if firstChoice and secondChoice have a value, then it may continue executing the code, other wise then return the "page".

Technically we are "guarding" to make sure that there is a value before continuing the execution, if there is no value then we stop the execution and return something.

Consider the following example:

var user: String?

func checkIfUserExist(){

    // if "user" has no value it will execute the code inside the else clause, and exit the scope
    guard user != nil else { print("User is nil"); return } 

    // If "user" has a value it will execute this code
    print("user is not nil")
}

checkIfUserExist()

hope this helps