Throwing swift error with specific error type in method signature

Question

With the new swift error handling introduced in 2.1 is it possible to specify a given ErrorType a method will throw?

e.g. class func nextOrderDate() throws OrderError -> NSDate {...}

Answer 1

In Swift, instead of throwing a specific type, you catch specific types, like this:

do {
   let date = try nextOrderDate() 
} catch let error as OrderError {
   print("OrderError")
} catch {
   print("other error")
}

A workaround that I have seen many times, is to return the error instead (very often seen in completion blocks):

class func nextOrderDate() -> (NSDate?, OrderError?)

SWIFT 5

You can now use:

class func nextOrderDate() -> Result<NSDate, OrderError>