How to solve this question that involves function and optionals? - swift

Question

I'm done with the first part, I need help with second question that involves updating the function to return an Int. I've tried to solve it but what I get is an error
If an app asks for a user's age, it may be because the app requires a user to be over a certain age to use some of the services it provides. Write a function called checkAge that takes one parameter of type String. The function should try to convert this parameter into an Int value and then check if the user is over 18 years old. If he/she is old enough, print "Welcome!", otherwise print "Sorry, but you aren't old enough to use our app." If the String parameter cannot be converted into an Int value, print "Sorry, something went wrong. Can you please re-enter your age?" Call the function and pass in userInputAge below as the single parameter. Then call the function and pass in a string that can be converted to an integer.
Go back and update your function to return the age as an integer. Will your function always return a value? Make sure your return type accurately reflects this. Call the function and print the return value.
func checkage(age: String)->Int?
{
if let age_type = Int(age)
{
if age_type > 18 {
return "Welcome!"
}
else if age_type < 18 {
return"Sorry, but you aren't old enough to use our app."
}
}
else {
return "Sorry, something went wrong. Can you please re-enter your age?"
}
return age_type
}
print(checkage(age:"23"))
error: 3. Exercise - Functions and Optionals.xcplaygroundpage:20:12: error: use of unresolved identifier 'age_type'
return age_type
^~~~~~~~

Answer 1

Several issues:
Inside your method, it looks like you're returning strings, but the method signature (checkage(age: String) -> Int?) indicates you're returning an optional integer value.
Your age_type is a non-optional value, but you're using if let, which is one way to unwrap optionals. No idea what's up there.
Your age_type declaration is less than or greater than, but if it's exactly equal, you'd hit your else block indicating there's something wrong, but that would be exactly age (assuming it would work, which it won't).
Anyway, here's a cleaned up version of what I think you're trying to do.
Based on your declarations in what you originally wrote, I think you may or may not have an age, so if you don't have one, you want to return an error. With that assumption, I made the age parameter optional (?). The guard statement checks if there's an age, if there is one, it unwraps it, otherwise it returns a string saying it ****ed up.
If it gets past the guard, then if it's over 18, it returns the "Welcome" string, otherwise it returns an error.
func check(age: Int?) -> String {
guard let age = age else {
return "Sorry, something went wrong. Can you please re-enter your age?"
}
if age > 18 {
return "Welcome!"
} else {
return "Sorry, but you aren't old enough to use our app."
}
}
Here are the outputs for the various ranges:
// Sorry, something went wrong. Can you please re-enter your age?
print(check(age: nil))
// Welcome!
print(check(age: 19))
// Sorry, but you aren't old enough to use our app.
print(check(age: 18))
Additionally, if you're writing a function to evaluate a number, it should take a number as a parameter. If you're getting the number from a textField, do the conversion from text to string on the view. If you're using a text field to get the number, look up ways to restrict input in the text field to a valid number string (your hint is look up UITextFieldDelegate methods.