handling Throw exception in Swift

In Swift, you can throw an exception by using the throw keyword followed by an error object. Here is an example:

enum MyError: Error {
    case badInput
    case fileNotFound
}
func processFile(filename: String) throws {
    if filename.isEmpty {
        throw MyError.badInput
    } else if !FileManager.default.fileExists(atPath: filename) {
        throw MyError.fileNotFound
    }
    // process file here
}

In this example, we define an enumeration of errors called MyError. We then define a function called processFile that takes a file name as a parameter and may throw an exception if the file name is empty or if the file doesn't exist.

When you call this function, you can use a do-catch block to catch and handle any thrown exceptions like so:

do {
    try processFile(filename: "file.txt")
} catch MyError.badInput {
    print("Bad input!")
} catch MyError.fileNotFound {
    print("File not found!")
} catch {
    print("Unknown error!")
}

In this example, if the processFile function throws an exception of type MyError.badInput, the message "Bad input!" will be printed to the console. Similarly, if it throws an exception of type MyError.fileNotFound, the message "File not found!" will be printed instead. If it throws any other exception, the message "Unknown error!" will be printed.