iOS Swift base64encoding与PAW应用程序Base64 Encoding不同

Question

Hoping to get some help with this. I am trying to post an image to a server and it requires base64 encoding of a PNG file. When I use the PAW app and encode the image everything shows up on the server beautifully. When I attempt to do the same with iOS Swift 4, the string produced is similar but also has differences and thus an incorrect image. Any idea of how to match the string that is correctly created in the PAW app in iOS. I have included code below along with screenshots of the strings (small samples) created.

Thanks!

    let image : UIImage = UIImage(named:"STG.png")!
    let imageData = UIImagePNGRepresentation(image)
    var base64String = imageData?.base64EncodedString(options: [])

Answer 1

You are not comparing the same data at all. Loading the png into a UIImage and then converting the UIImage into a new png representation does not result in the same set of bytes at all.

You need to directly load the png file into a Data instance without doing any conversion.

let imageURL = Bundle.main.url(forResource: "STG", withExtension: "png")!
let imageData = try! Data(contentsOf: imageURL)
var base64String = imageData.base64EncodedString(options: [])

You might also need to try different options in the call to base64EncodedString .

Answer 2

Ok went down several rabbit holes and found some folks with similar issues to this. I eventually solved it by switching over to Alamofire instead of using the native urlsession. I also found out the server I was posting to would allow for multipart/form-data as well which I ended up using for my request. I was unable to get that to work using the native urlsession either.