How can I implement protocols in method parameters in swift? - ios

Question

I'd like to implement protocol methods in the other method parameters.
First, I defined a protocol containing a method,
protocol MyProtocol {
func myProtocolFunc();
}
and I made a method taking the protocol as a parameter.
func myFunc(myProtocol : MyProtocol) {
. . .
}
and when I using this method, I want to override protocolFunc().
myFunc( . . . )
Where should I override protocolFunc() in my myFunc() method?
p.s. In Kotlin, I made that by doing like this.
interface MyProtocol {
fun myProtocolFunc();
}
fun myFunc(myProtocol : MyProtocol) {
. . .
}
myFunc(object : MyProtocol {
override fun myProtocolFunc() {
. . .
}
})
I want to do same thing in swift code.
========================================
Edit:
Actually, I'm planning to make Http Request class.
After getting some data from web server, I'd like to do some work in ViewController class.
Because Http Request runs on thread, while fetching some data from web server, next code regarding the data should wait.
Here is my Http Request class,
class HttpConnector {
static let basicURL = "http://******"
static func getData(url : String, parameters : String, listener : UIModifyAvailableListener) {
if let fullURL = URL(string : "\(basicURL)\(url)") {
var request = URLRequest(url : fullURL)
request.httpMethod = "POST"
request.httpBody = parameters.data(using: .utf8)
let task = URLSession.shared.dataTask(with: request, completionHandler: { data, response, error in
guard let data = data, error == nil else {
print("error = \(error!)")
return
}
if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {
print("statusCode should be 200, but is \(httpStatus.statusCode)")
print("response = \(response!)")
}
if let result = String(data: data, encoding: .utf8) {
listener.taskCompleted(result: result)
}
})
task.resume()
}
}
}
protocol UIModifyAvailableListener {
func taskCompleted(result : String)
}
and this class might be called in ViewController like this
HttpConnector.getData("my_url", "my_parameter", [[some codes regarding UIModifyAvailableListener protocol]])
If it can't be done in swift, I want to get some alternatives.

Answer 1

In your protocol, change the function to a variable of a function.
protocol UIModifyAvailableListener {
var taskCompleted : ((result : String) -> Void)? {get set}
}
Then in your HttpConnector class that implements UIModifyAvailableListener, add this:
var taskCompleted : ((result : String) -> Void)?
Within HttpConnector class's method(s), you can call taskCompleted like so:
self.taskCompleted?(result)
Then in the calling code that wants to be called back with taskCompleted(), simply set the var:
myHttpConnector.taskCompleted =
{
print("Done!") // note if you want to reference self here, you'll probably want to use weakSelf/strongSelf to avoid a memory leak.
}
BTW, this is an important pattern if you're doing MVVM, so that your ViewModel can call back into the ViewController. Since the ViewModel would never have a reference to its ViewController, all it can do is have callback properties that the ViewController can set with the closure blocks of code it wants called. And by using a protocol the ViewModel can be mocked when doing unit tests against the ViewController. :)