问题
I've a very strange issue I could't solve. I'm developing an iOS app using swift. In a class (class A), I call another class (class B) for connecting to a server. This server return a json, I pass the result to class A but I get an important delay for the operation I wish.
Here's the code of class A:
func loginUser () {
//check for data
if txt_mail!.text == "" || txt_password!.text == ""{
var alertView = UIAlertView(title: "Error", message: "no data", delegate: nil, cancelButtonTitle: "OK")
alertView.show()
}
else
{
//save data and login
var data:NSMutableDictionary = NSMutableDictionary(objects: [txt_mail!.text, txt_password!.text], forKeys: ["email", "password"])
loginUserClass().loginUser(data)
}
}
in class B i have:
func loginUser (data:NSMutableDictionary) {
var success_login:Int = 0
userData = data
//request for login
var request = NSMutableURLRequest(URL: NSURL(string: "http://link_to_server")!)
var session = NSURLSession.sharedSession()
request.HTTPMethod = "POST"
let email:String = userData.valueForKey("email") as! String
let password:String = userData.valueForKey("password") as! String
let auth:NSMutableDictionary = ["email":email,"token":password]
var err: NSError?
request.HTTPBody = NSJSONSerialization.dataWithJSONObject(params, options: nil, error: &err)
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
var task = session.dataTaskWithRequest(request, completionHandler: {data, response, error -> Void in
var err: NSError?
var json_return_server = NSJSONSerialization.JSONObjectWithData(data, options: .MutableLeaves, error: &err) as? NSDictionary
if(err != nil) {
//error
success_login = 0
}
else {
success_login = 1
}
}
/*
Now I call another func in class A for "working" the result
*/
dispatch_async(dispatch_get_main_queue(), {
loginWithMailScreen().LoginUser_result(success_login)
})
})
task.resume()
}
so the func that works the result in class A is:
func LoginUser_result (success:Int) {
if success == 1{
print("Success...")
let alert = UIAlertView(title: "Good", message: "Success...", delegate: nil, cancelButtonTitle: "Ok")
alert.show()
}
else if success == 0{
print("Error...")
let alert = UIAlertView(title: "Error", message: "I'm sorry", delegate: nil, cancelButtonTitle: "Ok")
alert.show()
}
}
It's strange because console prints "Success..." or "Error..." very quickly but app shows alert after about 10 seconds!!! Any idea about the reason and how I could solve???
PS: sorry for my bad english, I'm italian
EDIT: I think server is very fast, in fact like I said I've the right result (0 for wrong mail/password, 1 for right mail/password). the strange behavior, I guess, is the delay for alert
I edit my code like Sulthan suggested. There's another issue with code like that. In fact, I get no problem with alert (no delay) but no other function is possible (dismiss isn't working)!!!
Any idea?
回答1:
You are updating ui on from background thread. You have to update UI from main thread only.
dispatch_async(dispatch_get_main_queue(), {
loginWithMailScreen().loginUser_result(success_login)
})
来源：https://stackoverflow.com/questions/32547831/very-strange-issue-in-swift-code-delay-to-make-operations