如何在此Swift函数中减少return false的数量

Question

I get the feeling all the "return false" statements in this function might be redundant. I encounter a similar scenario often. I would like to avoid the bloat of any extra code.

Question: Is there a way to reduce the quantity of the "return false" statements and still have the function do the same thing?

For context, I am trying to efficiently check an array of Int in UserDefaults to see if it contains a particular integer.

func isItemNumberInList(itemNumber : Int) -> Bool{

    if UserDefaults.standard.object(forKey: "myList") != nil{
        if var myList : [Int] = UserDefaults.standard.object(forKey: "myList") as? [Int]{
            if myList.index(of: itemNumber) != nil {
                return true
            }else{
                return false
            }
        }else{
            return false
        }
    }else{
        return false
    }

}

Answer 1

There is indeed a way

func isDockNumberInList(dockNumber : Int) -> Bool {
    guard let myList = UserDefaults.standard.array(forKey: "myList") as? [Int],
        myList.contains(dockNumber) else { return false }
    return true
}

or

func isDockNumberInList(dockNumber : Int) -> Bool {
    guard let myList = UserDefaults.standard.array(forKey: "myList") as? [Int] else { return false }
    return myList.contains(dockNumber)
}

Answer 2

The simplest solution is to delete your first if statement, since it is completely redundant due to the fact that the conditional binding can only succeed if the value is non-nil. Then you can also merge the two inner if statement into one, since you only care whether both are true or not.

func isItemNumberInList(itemNumber : Int) -> Bool{
    if let myList = UserDefaults.standard.object(forKey: "myList") as? [Int], myList.index(of: itemNumber) != nil {
       return true
    } else {
        return false 
    }
}

The else statement can be omitted is well, since in case the if statement evaluates to true, the function will exit by returning true, so the return false expression can only be reached in case the if statement before evaluated to false.

func isItemNumberInList(itemNumber : Int) -> Bool{
    if let myList = UserDefaults.standard.object(forKey: "myList") as? [Int], myList.index(of: itemNumber) != nil {
       return true
    }
    return false 
}