How do I save an image to a png file? - swift

Question

How do I load an image from specified url and save it to an existing local png file ? I'm trying to do it as follow but get an error
The file couldn’t be saved because the specified URL type isn’t supported
let url = URL(string: urlString)
let data = try? Data(contentsOf: url!)
try data?.write(to: URL(string: "icon.png")!)

Answer 1

First of all never use synchronous Data(contentsOf to load data from a server.
The error occurs because the URL has the wrong format
A remote URL must contain a scheme and host (http://server.com...)
An local URL in the file system must be created with URL(fileURLWithPath: and the path must start with a slash.

Answer 2

Use the following code to asynchronously download a file:
extension FileManager {
open func secureCopyItem(at srcURL: URL, to dstURL: URL) -> Bool {
do {
if FileManager.default.fileExists(atPath: dstURL.path) {
try FileManager.default.removeItem(at: dstURL)
}
try FileManager.default.copyItem(at: srcURL, to: dstURL)
} catch (let error) {
print("Cannot copy item at \(srcURL) to \(dstURL): \(error)")
return false
}
return true
}
}
func download() {
let storagePathUrl = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as NSString).appendingPathComponent("file.png")
let fileUrl = "https://server/file.png"
let urlRequest = URLRequest(url: URL(string: fileUrl)!)
let task = URLSession.shared.downloadTask(with: urlRequest) { tempLocalUrl, response, error in
guard error == nil, let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode == 200 else {
print("Error")
return
}
guard FileManager.default.secureCopyItem(at: tempLocalUrl!, to: storagePathUrl) else {
print("Error")
return
}
}
task.resume()
}