Http request using Alamofire

Question

I'm using Alamofire to send HTTP request in my App. I'm using a TabBarViewController, In first view's ViewDidLoad, I send a request. Also in ViewWillDisappear, I send another request. However, I found it behave unexpected when I changing the tabs.

func sendHttpCommand(parameter: NSDictionary) {
    Alamofire.request(.GET, URL, parameters: (parameter as! [String: AnyObject]))
             .response {
                 request, response, data, error in
                 print(request)
             }
}

viewDidLoad() {
    let dict: NSDictionary = ["value": 0]
    sendHttpCommand(dict)
}

viewWillDisappear(animated: Bool) {
    let dict: NSDictionary = ["value": 1]
    sendHttpCommand(dict)
}

When I switching the tabs, in NORMAL CASE, my console will print out

Optional(NSMutableURLRequest {URL: xxxxx/value=0})
Optional(NSMutableURLRequest {URL: xxxxx/value=1})
Optional(NSMutableURLRequest {URL: xxxxx/value=0})
Optional(NSMutableURLRequest {URL: xxxxx/value=1})
Optional(NSMutableURLRequest {URL: xxxxx/value=0})
Optional(NSMutableURLRequest {URL: xxxxx/value=1})
Optional(NSMutableURLRequest {URL: xxxxx/value=0})
Optional(NSMutableURLRequest {URL: xxxxx/value=1})

However, when I switching the tabs fast enough, my console will print out

Optional(NSMutableURLRequest {URL: xxxxx/value=0})
Optional(NSMutableURLRequest {URL: xxxxx/value=1})
Optional(NSMutableURLRequest {URL: xxxxx/value=1})
Optional(NSMutableURLRequest {URL: xxxxx/value=0})
Optional(NSMutableURLRequest {URL: xxxxx/value=0})
Optional(NSMutableURLRequest {URL: xxxxx/value=1})
Optional(NSMutableURLRequest {URL: xxxxx/value=1})
Optional(NSMutableURLRequest {URL: xxxxx/value=0})

Any ideas?

score 2 · Answer 1 · edited May 23 '17 at 11:45

2

the alamofire requests are executed async.

Read here to understand asyncs and syncs: Difference between dispatch_async and dispatch_sync on serial queue?

You can cancel your alamofire request when you change the tab and the request is not finished. For this you need an Alamofire Manager.

edited May 23 '17 at 11:45

Community

1
1

answered Mar 31 '16 at 09:14

Sebi

71
1
4

How can I make the request in order? I tried to use `dispatch_group`. However, i seems not working. [link](http://stackoverflow.com/questions/28100847/checking-for-multiple-asynchronous-responses-from-alamofire-and-swift) – Willjay Apr 01 '16 at 02:43
you have to call the next request in your response handler. Or use a delegate and fire it in your response handler to start the next request. You can also cancel your request if the user changes the tab http://stackoverflow.com/questions/26305707/how-to-pause-resume-cancel-my-download-request-in-alamofire – Sebi Apr 01 '16 at 09:36

Http request using Alamofire

1 Answers1