Xcode Tutorial: How to Make a Clock

Here is my first tutorial for Xcode and Objective-C - How to make a clock on the iPhone.  It is really simple and can be created many different ways.  The source code is available after the break.

Code:

.h File:

@interface ViewController : UIViewController {

    

    IBOutlet UILabel *lblTime; //Make sure to connect this to the label in the storyboard/xib

    

    NSDate *currentTime;

    NSTimer *updateTimer;

}

.m File:

- (void)viewDidLoad

{

    [self updateTime];

    

    [super viewDidLoad]; 

    // Do any additional setup after loading the view, typically from a nib.

}

//Updates the timer

- (void)updateTime {

    

    // Without this, the timer would never be erased from the code.
    // This would cause a memory overload.

    [updateTimer invalidate]; 

    updateTimer = nil;

    

    currentTime = [NSDate date];

    NSDateFormatter *timeFormatter = [[NSDateFormatter alloc] init];

    [timeFormatter setTimeStyle:NSDateFormatterMediumStyle];

    lblTime.text = [timeFormatter stringFromDate:currentTime];

    

    updateTimer = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(updateTime) userInfo:nil repeats:YES];

}