Question

我在视图控制器中的函数内部已经有了所有这些代码：

self.activityIndicator.startAnimating()

let url = NSURL(string: "http://www.google.com")

var request = NSMutableURLRequest(URL: url!)
request.HTTPMethod = "PUT"

var err: NSError?
request.HTTPBody = NSJSONSerialization.dataWithJSONObject(["notes": self.textView.text], options: nil, error: &err)
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
var s = NSString(data: request.HTTPBody!, encoding: NSUTF8StringEncoding)

let task = NSURLSession.sharedSession().dataTaskWithRequest(request, completionHandler: { (data, reponse, error) -> Void in

    // ------------------
    // This doesn't work
    // ------------------
    self.activityIndicator.stopAnimating()


    println(NSString(data: data, encoding: NSUTF8StringEncoding))
})
task.resume()

我希望我的活动指示器在我完成任务时停止动画，但是调用stopAnimating（）没有做任何事情 - 甚至没有抛出任何错误。谁知道我做错了什么？

Answer 1

您需要在主UI线程上执行此操作，如下所示：

    // ------------------
    // This should work :-)
    // ------------------
dispatch_async(dispatch_get_main_queue(), {

        // DO SOMETHING ON THE MAINTHREAD
        self.activityIndicator.stopAnimating()
        })

Answer 2

在主线程上执行：

let task = NSURLSession.sharedSession().dataTaskWithRequest(request) { (data, reponse, error) -> Void in

    dispatch_async(dispatch_get_main_queue()) {
        self.activityIndicator.stopAnimating()
    }
    println(NSString(data: data, encoding: NSUTF8StringEncoding))

}

Swift中的变量范围与任务

2 个答案: