Noop For Swift'S Exhaustive Switch Statements

Noop for Swift's Exhaustive Switch Statements

According to the book, you need to use break there:

The scope of each case can’t be empty. As a result, you must include at least one statement following the colon (:) of each case label. Use a single break statement if you don’t intend to execute any code in the body of a matched case.

How do I create a noop block for a switch case in Swift?

default:
  break

Apple talks about this keyword in this article. See here, too.

Although break is not required in Swift, you can still use a break statement to match and ignore a particular case, or to break out of a matched case before that case has completed its execution.

Exhaustive condition of switch case in Swift

Swift only truly verifies that a switch block is exhaustive when working with enum types. Even a switching on Bool requires a default block in addition to true and false:

var b = true
switch b {
case true:  println("true")
case false: println("false")
}
// error: switch must be exhaustive, consider adding a default clause

With an enum, however, the compiler is happy to only look at the two cases:

enum MyBool {
    case True
    case False
}

var b = MyBool.True
switch b {
case .True:  println("true")
case .False: println("false")
}

If you need to include a default block for the compiler's sake but don't have anything for it to do, the break keyword comes in handy:

var b = true
switch b {
case true:  println("true")
case false: println("false")
default: break
}

Switch statement must be exhaustive

Xcode checks if the switch statement is exhaustive only if you're switching enums. For every other case, it checks if there is a default statement, and if not, it puts up a warning.

You can either use enums, or squelch the warning if you want to, or, just add the missing default statement doing nothing.

Switch must be exhaustive in Xcode 12

In WWDC 2020, iOS 14 Apple introduced a new feature that will give limited access to the photo library. You are missing .limited case for outer main Switch. Your updated code:

switch PHPhotoLibrary.authorizationStatus(for: .readWrite) {
case .notDetermined:
    // ask for access
case .restricted, .denied:
    // sorry
case .authorized:
    // we have full access
 
// new option: 
case .limited:
    // we only got access to a part of the library
}

For More, you can check here

Non-exhaustive pattern match for Swift enum

if [.One, .Two, .Three, .Four].contains(num) {

Swift switch statement force to write block of code

Just get your function to return in that case:

case .hamburger:
    return

Hope that helps.

Per the discussion and @MartinR 's comment, break is probably a better general solution to exit the switch statement.

---

Related Topics