objetive-c example for apple app

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@property (weak, nonatomic) IBOutlet UITextField *waterTextField;
@property (weak, nonatomic) IBOutlet UITextField *ratioTextField;
@property (weak, nonatomic) IBOutlet UITextField *coffeeTextField;


- (IBAction)calculateButtonPressed:(id)sender;

@end

// viewController.m

#import "ViewController.h"

@implementation ViewController
@synthesize waterTextField;
@synthesize ratioTextField;
@synthesize coffeeTextField;

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
}

- (void)viewDidUnload
{
    [self setWaterTextField:nil];
    [self setRatioTextField:nil];
    [self setCoffeeTextField:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
}

- (void)viewWillDisappear:(BOOL)animated
{
	[super viewWillDisappear:animated];
}

- (void)viewDidDisappear:(BOOL)animated
{
	[super viewDidDisappear:animated];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
    } else {
        return YES;
    }
}

- (IBAction)calculateButtonPressed:(id)sender {
    NSLog(@"Calculate Pressed");
    
    float water = [[self.waterTextField text] floatValue];
    float ration = [[self.ratioTextField text] floatValue];
    
    NSLog(@"water: %f ration: %f", water, ration);
    
    float coffee = water/ration;
    
    NSString *coffeeText = [NSString stringWithFormat:@"%f", coffee];
    coffeeTextField.text = coffeeText;
    
}
@end