I know this error is a common message and has already been the subject of many posts. However, as a pure beginner who just started days ago, I can't really understand the solution on other posts, and also haven't learned what Switch means. Thefore, that solution can't be used with me. Here's my block code getting the error :
func responseTo(question: String) -> String {
let lowercasedQuestion = question.lowercased()
if lowercasedQuestion.hasPrefix("hello") {
if lowercasedQuestion.hasPrefix("Hello") {
return "Why, hello there!"
} else if lowercasedQuestion.hasPrefix("where") {
if lowercasedQuestion.hasPrefix("Where") {
return "To the North"
} else {
return "Where are the cookies?"
}
}
}
}
I tried to put the last else outside the first if since I read it could change the output and remove the error, but it didn't change anything. I tried to enter return nil on the last line, but had an error. What can I do? Any answer appreciated.
CodePudding user response：
Your responseTo(String) -> String function must return a String. You must consider this case, if the parameter (question) doesn't start with "hello", the function doesn't have any String to return.
let result: String = responseTo("asd") // error
As stated in the comments, there are several ways to solve this. If your function must return a string, then consider returning a default value at the end. The return value can be an empty string (but whatever your default value is, make sure to handle it properly).
func responseTo(question: String) -> String {
let lowercasedQuestion = question.lowercased()
if lowercasedQuestion.hasPrefix("hello") {
//
} else {
return "" // this will be the default return value
}
}
or
func responseTo(question: String) -> String {
let lowercasedQuestion = question.lowercased()
if lowercasedQuestion.hasPrefix("hello") {
//
}
return "" // this will also be the default return value
}
Another way is to return an Optional String (String?). The reason why return nil doesn't work for responseTo(String) -> String is because it must return a string. To be able to return a nil, you will have to change the declaration of your function to responseTo(String) -> String?.
func responseTo(question: String) -> String? { // the "?" after String notifies the compiler that this function can return a String or a nil
let lowercasedQuestion = question.lowercased()
if lowercasedQuestion.hasPrefix("hello") {
//
}
return nil
}