convert NSData to NSString always return nil - nsstring

Question

I have a problem that I can't successfully convert NSData to NSString
I use google drive sdks to get content of my google doc using
var fetcher:GTMHTTPFetcher = service.fetcherService.fetcherWithURLString(downloadurl as! String)
fetcher.beginFetchWithCompletionHandler({(olddata:NSData!, error:NSError!) in
if(error == nil) {
print(olddata)
}
else {
print("error is \(error)")
}
})
olddata was a NSData (with no optional)
And I want to convert to NSString
but it always return nil when using basic conversion
let myStringFromData = NSString(data: olddata, encoding: NSUTF8StringEncoding)
how can i fix this

Answer 1

import Foundation
let string = "what i would like to send to server as utf8 text"
var utf8text = string.utf8.map { $0 }
utf8text.append(0)
let data = NSData(bytes: &utf8text, length: utf8text.count)
// ..... upload, download, data is now received NSData from server
let p = UnsafePointer<Int8>(data.bytes)
if let received = String.fromCString(p) {
print(received) // what i would like to send to server as utf8 text
}else {
print("error by reconstructing string from data")
}
or
let string = "what i would like to send to server as utf8 text"
var buffer = string.nulTerminatedUTF8.map{ $0 }
let data = NSData(bytes: &buffer, length: buffer.count)
// ..... upload, download, data is now received NSData from server
let p = UnsafePointer<Int8>(data.bytes)
if let received = String.fromCString(p) {
print(received) // what i would like to send to server as utf8 text
}else {
print("error by reconstructing string from data")
}
or
let buffer = "what i would like to send to server as utf8 text".nulTerminatedUTF8
let data = buffer.withUnsafeBufferPointer {
NSData(bytes: $0.baseAddress, length: $0.count)
}