ios - example - DispatchQueue.main.sync que devuelve exc_bad_instruction Swift 3

nsoperationqueue swift 3 example

Question

Quiero mostrar un ActivityIndicatorView en mi aplicación, pero cuando llamo al método de sync desde el hilo principal, la aplicación falla con el error: exc_bad_instruction (code=exc_i386_invop subcode=0x0) Estoy usando xcode 8.0 y swift 3

¿Puede alguien ayudarme?

 func POST(endpoint:NSString!,body:NSString!,vc:UIViewController? = nil)->NetworkResult{
let result = NetworkResult()
DispatchQueue.main.sync {
self.displayActivityIndicator(viewController: vc)
}
let urlStr = self.url.appending(endpoint as String).appending(self.getHashAutenticacao() as String)
print(urlStr)
let request = NSMutableURLRequest(url: URL(string: urlStr)!, cachePolicy: NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData, timeoutInterval: 20)
print(request.debugDescription)
request.setValue("application/json", forHTTPHeaderField: "Accept")
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
request.httpMethod = "POST"
request.httpBody = body.data(using: String.Encoding.utf8.rawValue, allowLossyConversion: true)
// send the request
var data: NSData!
do {
data = try NSURLConnection.sendSynchronousRequest(request as URLRequest, returning: &self.response) as NSData!
} catch let error1 as NSError {
self.error = error1
data = nil
}
if let httpResponse = self.response as? HTTPURLResponse {
result.resultCode = httpResponse.statusCode
if httpResponse.statusCode == 200{
if data != nil{
if data.length > 0{
let json = (try! JSONSerialization.jsonObject(with: data as Data, options: JSONSerialization.ReadingOptions.mutableContainers))
if let jsonArray:NSArray = json as? NSArray{
result.data = jsonArray
}else{
if let jsonDict:NSDictionary = json as? NSDictionary{
result.data = [jsonDict]
}
}
}
}
}
}else {
result.message = self.error!.debugDescription as NSString?
}
DispatchQueue.main.sync {
self.hideActivityIndicator(viewController: vc)
}
return result
}

Answer 1

Lo que intenta hacer aquí es lanzar el hilo principal de forma sincrónica desde un hilo de fondo antes de que salga. Este es un error logico

Deberías hacerlo así:

DispatchQueue.global().async(execute: {
print("teste")
DispatchQueue.main.sync{
print("main thread")
}
})