iOS develops multi-threaded articles---communication between threads

The performance of inter-thread communication:

1 Threads pass data to another 1 threads

After performing a specific task in 1 threads, go to another 1 thread to continue the task

Here is an example of downloading a picture:

@interface  BTThreadViewController  () {    uiimageview *imagev;} @end-  (void) viewdidload{    [super viewdidload];         imagev = [[uiimageview alloc] initwithframe:cgrectmake (100, 100,  100, 100)];    [self.view addsubview:imagev];         //child thread Inside call downimage method download Picture     [self performselectorinbackground : @selector (Downimage)  withobject:nil];} -(void) downimage{    //download pictures from the network     nsurl *url = [nsurl  urlwithstring:@ "Http://i8.topit.me/8/c1/31/1142319854bdc31c18o.jpg"];    // Convert a picture to binary data     NSData *imgData = [NSData dataWithContentsOfURL:url]; Convert     //data into pictures     UIImage *img = [UIImage  Imagewithdata:imgdata];        //back to main thread settings picture     [self  Performselectoronmainthread: @selector (senderimage:)  withobject:img waituntildone:no];} -(void) Senderimage: (uiimage *) image{    imagev.image = image;}

iOS develops multi-threaded articles---communication between threads