Objective-C：仅在另一个类中完成NSURLSession和NSXMLParser委托后，才在当前类中执行函数

Question

I have a Class1 in which I have to load a UITableView row on didSelectRowAtIndexPath . In this didSelectRowAtIndexPath i make a call to a method in Class2 which thereby calls NSURLSession delegates and NSXMLParser delegates. I want to get the value of this parsed data and reload the UITableView row in Class1 .

I want to reload UITableView only after I get the data. As the Delegate methods are asynchronous I am not able to get the data and so I get an empty UITableView row.

What can be the solution?

Answer 1

On completion of data pulling and parsing in Class2, let Class1 know:

[[NSNotificationCenter defaultCenter] postNotificationName:@"kDataIsReady" object:@{@"key":@"value"}];

You need to register Class1 as a listener early on (eg in viewDidLoad):

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(dataReady:) name:@"kDataIsReady" object:nil];

Which then calls this method in Class1:

-(void)dataReady:(NSNotification *)n {

    NSDictionary * d = n.object; 
    NSString * value = d[@"key"];
    //e.g. update your data array, refresh tableView / specific cell
}