Make some calculation on Viewcontroller, need show the result to another Viewcontroller - ios

Question

I have an app, where I making some calculation, and need to transfer result of this calculation to ViewController3 and show the result there. Now I use label in same ViewController2 where I have calculation. Thank you for your help.
ViewController2.h
#import <UIKit/UIKit.h>
#interface ViewController2 : UIViewController<UITextFieldDelegate>
#property (weak, nonatomic) IBOutlet UILabel *gasPrice;
#property (weak, nonatomic) IBOutlet UILabel *gasCarMileage;
#property (weak, nonatomic) IBOutlet UITextField *perGalon;
#property (weak, nonatomic) IBOutlet UITextField *miles;
#property(nonatomic, copy, readonly) NSString *result;
- (IBAction)getIt:(id)sender;
#end
ViewController2.m
#import "ViewController2.h"
#import "ViewController3.h"
#interface ViewController2 ()
#end
#implementation ViewController2
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
//Start calculation
- (IBAction)getIt:(id)sender; {
float perGalon = ([_perGalon.text floatValue]);
float miles = ([_miles.text floatValue]);
float mileCost = perGalon / miles;
[self performSegueWithIdentifier:#"viewController3" sender: nil];
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"viewController3"]) {
ViewController3 *viewController3 = [segue destinationViewController];
viewController3.result = [[NSString alloc] initWithFormat: #"Every mile you drive
will cost you $ %f", mileCost];
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
self.perGalon.delegate = self;
self.miles.delegate = self;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
return [textField resignFirstResponder];
}
#end
ViewController3.h
#import <UIKit/UIKit.h>
#interface ViewController3 : UIViewController
#property(nonatomic, copy) NSString *result;
#end
ViewController3.m
#import "ViewController3.h"
#import "ViewController2.h"
#interface ViewController3 ()
#end
#interface ViewController2 ()
#property(nonatomic, copy, readwrite) NSString *result;
#end
#implementation ViewController3
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

You can define a string property in View controller 3 which you will set when you push view controller 3 from view controller 2.
ViewController3 interface declaration
#interface ViewController2 ()
#property(nonatomic, copy) NSString *result;
#end
In ViewController 2, you will implement this line at the last of your getIt() method.
[self performSegueWithIdentifier:#"viewController3" sender: nil]
And implement another method called prepareForSegue as follows
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"viewController3"]) {
ViewController3 *viewController3 = [segue destinationViewController];
viewController3.result = "YOUR CALCULATION RESULT HERE"
}
}
Bear in mind, you have to set identifier for view controller 3, go to storyboard and select the view for view controller 3 and On identify inspector, specified Storyboard ID as "viewController3".

Answer 2

Use a protocol,
In ViewController2.h
#protocol ViewController2Delegate;
#property (strong, nonatomic) id<ViewController2Delegate> delegate;
#protocol BexAPIClientDelegate <NSObject>
- (void)ViewController2:(ViewController2 *)vc didCalculateCost:(CGFloat)cost;
#end
Then at the end of the getIt() call the delegate
[self.delegate viewController2:self didCalculateCost:gasCostPerMile];
You need to set ViewController3 to be ViewController2's delegate when you load it. Also you will need to setup ViewController3 to conform to the protocol.
Using the protocol is worth the effort as it will make your code clear and easy to manage.

Answer 3

Retain a string in VC3. While initializing the VC3 object, set the value from VC2. Update the label in VC3(in viewDidLoad method)