Moya/Alamofire request variables issue

Question

I am writing an iOS app in Swift and using Moya as Network layer.

I am making a request object to be send in body and using Moya to perform API call:

struct OrderRequest{
var amount:Double
}

let order=OrderRequest(amount:100.57)

I am converting this object to JSONDict and then to Data.

if let json = JSONDict(from: order) {
  let data = try JSONSerialization.data(withJSONObject: json, options: [])
}

I am performing Moya request and internally it's using Alamofire .

ISSUE:

Instead of sending the accurate value of 100.57 , it sends 100.56999999999999

My question is about below line:

let jsonString = String(data: jsonData!, encoding: .utf8)

It converts data from DATA to STRING. This is converting 100.57 to 100.56999999999999

How can it be solved? Am I making the DATA object incorrectly?

Answer 1

That's how binary floating point arithmetic works. About 15 digits precision for Double , and much less for Float . What's wrong is not the code, but your expectations. And this is the same in C, C++, Objective-C, Java and so on. Also here you can find the same issue