ios - update UI inside block - ios

Question

I make a call to the youtube API to get the title of a video. I then want to display the title of the video on the screen in a table. How do I access the title after the block has finished executing?
Here's the code to get the title
-(void)getVideoTitle:(NSString *)urlStr success:(void (^)(NSDictionary *responseDict))success{
urlStr = [NSString stringWithFormat:#"https://www.googleapis.com/youtube/v3/videos?part=contentDetails%%2C+snippet%%2C+statistics&id=%#&key={API_KEY}",urlStr];
NSURL *url = [[NSURL alloc] initWithString:urlStr];
// Create your request
NSURLRequest *request = [NSURLRequest requestWithURL:url];
// Send the request asynchronously
[[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *connectionError) {
// Callback, parse the data and check for errors
if (data && !connectionError) {
NSError *jsonError;
NSDictionary *jsonResult = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&jsonError];
if (!jsonError) {
success(jsonResult);
// NSLog(#"Response from YouTube: %#", jsonResult);
}
}
}] resume];
}
Here's how I call the above function:
[self getVideoTitle:#"zB4I68XVPzQ" success:^(NSDictionary *responseDict){
NSArray *itemsArray = [responseDict valueForKey:#"items"];
NSDictionary *item = itemsArray[0];
NSDictionary* snippet = [item valueForKey:#"snippet"];
NSString *title = [snippet valueForKey:#"title"];
}];
How do I get access the title variable outside the block after the block has finished executing?
I have tried the following with no luck
dispatch_async(dispatch_get_main_queue(), ^{
[self updateMyUserInterfaceOrSomething];
});

Answer 1

In your code:
NSString* recievedTitle __block = nil; //title is here, after block below run
[self getVideoTitle:#"zB4I68XVPzQ" success:^(NSDictionary *responseDict){
NSArray *itemsArray = [responseDict valueForKey:#"items"];
NSDictionary *item = itemsArray[0];
NSDictionary* snippet = [item valueForKey:#"snippet"];
recievedTitle = [snippet valueForKey:#"title"]; //here you write it
// or
NSString *title = [snippet valueForKey:#"title"];
[self updateInterfaceWithTitle: title]
}];
///
- (void)updateInterfaceWithTitle:(NSString*)title{
//use title here
}