I've posted this as an answer on stackoverflow before, and the information was highly appreciated by some people. The question was like: “How to catch any error, specially unexpectedly found nil in Swift?" Though the author was asking about catching system errors, I decided to post my super-handy Unwrap Snippet there.
struct UnwrapError: Error, CustomStringConvertible {
let optional: T?
public var description: String {
return "Found nil while unwrapping \(String(describing: optional))!"
}
}
public func unwrap(_ optional: T?) throws -> T {
if let real = optional {
return real
} else {
throw UnwrapError(optional: optional)
}
} The idea of this approach is to replace multiple
if let and guard let statements with a single do-try-catch block. You can:
do {
// Parse JSON and assign variables which were defined somewhere above
let dictionary = try unwrap(JSONSerialization.jsonObject(
with: data,
options: .allowFragments) as? [String: Any])
isAdsEnabled = try unwrap(dictionary["isAdsEnabled"] as? Bool)
// While calling function which require a non-optional parameter in one line of code
imageView.image = try UIImage(data: unwrap(receivedData))
// And also you can simplify the building of multipart data
var data = Data()
data += try unwrap(dispositionString.data(using: .utf8))
data += someContent
data += try unwrap("\r\n".data(using: .utf8))
} catch error {
// Handle error
// ...
// and exit
return nil
}Those who make apps with web backend will definitely like.
