我在块内将值设置为 NSString 时遇到问题。
__block NSString *cityID = [[NSString alloc] init];
AFJSONRequestOperation *operation = [AFJSONRequestOperation
JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id json) {
cityID = [NSString stringWithFormat:@"%@",[[json valueForKeyPath:@"location"] valueForKey:@"id"]];
NSLog(@"city id for 621352674 = %@",cityID);
} failure:nil];
[operation start];
NSLog(@"city id for 621352674 = %@",cityID);
第一个 NSLog 显示了 cityID 的正确值。但第二个什么也没显示。如何解决这个问题?