I'm trying to display the current date and time on my iPad.

Question

First, I'm not sure this is a valid post to this forum.  If not, I'd appreciate knowg in where I can get help. 
I have tried several ways to display the current date and time on my iPad.  None  work.  Most things I try give me complier errors but the latest code compiles but won't display the correct time. 
Here's the dispatch code in my ViewController.m file:
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
    dispatch_async(queue, ^{
        [NSTimer scheduledTimerWithTimeInterval:NSTimeInterval)1.0f target:self selector:@selector(updateLabel:) userInfo:nil repeats:YES];
Here's the updateLabel code: (which never gets executed).
- (void)updateLabel:(id) sender {
    dispatch_sync(dispatch_get_main_queue(), ^{
    NSLog(@"Datefield Update Called");
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"EEEE, MMMM dd, yyyy 'at' HH:mm  ZZZZ"];
    NSDate *dayTime = [NSDate date];
    NSString *formattedDateString = [dateFormatter stringFromDate:dayTime];
        _dateField.text = formattedDateString;
    [self.view addSubview:_dateField];
    NSLog(@"Datefield %@",_dateField.text);

Answer 1

Your code is needlessly complicated and has a few problems:
// These objects should be created only once.
NSTimer *dateAndTimeTimer; (You might need to make this a property with a strong reference).
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:@"EEEE, MMMMM dd, yyyy 'at' HH:mm ZZZZ"];
// The subview should only be added once.
[self.view addSubview:_dateField];
[self performSelectorOnMainThread:@selector(startDateAndTimeTimer)
                        withObject:nil
                     waitUntilDone:YES];
-(void)startDateAndTimeTimer
    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1
                                                      target:self
                                                    selector:@selector(updateLabel)
                                                    userInfo:nil
                                                     repeats:YES];
    dateAndTimeTimer = timer;
    [[NSRunLoop mainRunLoop] addTimer:dateAndTimeTimer forMode:NSRunLoopCommonModes];
-(void)updateLabel
     NSDate *dateTime = [NSDate date];
     NSString *formattedDataString = [dateFormatter stringFromDate:dateTime];
     _dateField.text = formattedDateString;
     NSLog(@"_dateField.text=%@", _dateField.text);