Swift：将数据从 function 传递到变量时出现问题

Question

I am trying to pass data from a function to a declared variable,

   func request(platform:String, rankData:[String : [Model]]) {
 
        
        APIService.shared.get(api: "someURL", parameters:[platform: platform], completion: { (result: Result<ModelResult,AFError>) in

            switch result {
            case .success(let success):
                
                rankData = success.result
                self.collectionView.reloadData()
                
            case .failure(let failure):
                print(failure.errorDescription!)
            }
        })
        
  
    }

but I am getting this error

Cannot assign to value: 'rankData' is a 'let' constant

I added inout but still not working, also tried to add

 var aData = rankData 

but still, I cannot pass data to my variables and xcode give this warrning:

Variable 'aData' was written to, but never read

How I want to use:

var firstResult:[String : [Model]] = [:]
request(platform: "car", rankData: firstResult)

any help?

Answer 1

You cannot return something asynchronous through an inout parameter.

But the solution is pretty easy.

Replace

func request(platform:String, rankData:[String : [Model]]) {

with

func request(platform:String) {

And the line

rankData = success.result

with

self.firstResult = success.result