Data transfer between controllers with saving

Question

How to make data transfer between ViewController , i.e. from one controller to another?
I want to make data entry (settings) on one controller, and output this data on the other.
If you can, tell me an example, please!

 ViewController.h #import <UIKit/UIKit.h> #import "ViewController2.h" @interface ViewController : UIViewController @property (weak, nonatomic) IBOutlet UITextField *log; - (IBAction)vper:(id)sender; @end ViewController.m #import "ViewController.h" @interface ViewController () @end @implementation ViewController - (void) someButtonTapped:(id)sender { ViewController2 *classB = [[ViewController2 alloc] init]; //создаете экземпляр класса classB.textFieldValue = _log.text; // присваеваете значение переменной } - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } - (IBAction)vper:(id)sender { } @end ViewController2.h #import <UIKit/UIKit.h> #import "ViewController.h" @interface ViewController2 : UIViewController @property (nonatomic, strong) NSString *textFieldValue; @property (weak, nonatomic) IBOutlet UILabel *lab; - (IBAction)naz:(id)sender; @end ViewController2.m #import "ViewController2.h" @interface ViewController2 () @end @implementation ViewController2 - (void)viewDidLoad { NSLog(@"textFieldValue = %@", _textFieldValue); } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } - (IBAction)naz:(id)sender { } @end

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Accepted Answer · 2016-04-27T10:55:18

Suppose you have two classes, class A and class B Class А - data entry and class В - data processing. In the method in which we process the input data, you need to create an instance of class В

 - (void) someButtonTapped:(id)sender { MyClassB *classB = [[MyClassB alloc] init]; //создаете экземпляр класса classB.textFieldValue = _textField.text; // присваеваете значение переменной }

In your class B in the .h file, add the property

 @property (nonatomic, strong) NSString *textFieldValue;

Now the variable textFieldValue contains the value that you passed to it in class А

For example, in the viewDidLoad method (class B) you can check:

 - (void)viewDidLoad { NSLog(@"textFieldValue = %@", _textFieldValue); }

NB! Instance of the class, you need to create only once, if during the transition to the new view you make another instance, then the value of _textFieldValue will be nil .

UPDATE

Since you are creating a link to a new controller in IB , you need to configure segue . To do this in IB , highlight the connection between the first and second controller, in the Utilities tab, select Attributes and specify Identifier - for example, segueNext .

Further, in order to transfer data, you need a method

 - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

In which you specify the necessary connection, and transfer data to the controller. Here is an example:

 - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { if ([[segue identifier] isEqualToString:@"segueNext"]) { ViewController2 *classB = [segue destinationViewController]; classB.textFieldValue = _log.text; } }

Second option

Remove from the IB connection and make the transitions in the code. For example:

 - (IBAction)vper:(id)sender { ViewController2 *classB = [self.storyboard instantiateViewControllerWithIdentifier:@"ViewController2"]; classB.textFieldValue = _log.text; [self presentViewController:classB animated:YES completion:nil]; }

Only he swears at _textField.text in (void) someButtonTapped (use of undeclared identifier '_textfield'), what to do?
Or first, just classB.textFieldValue = @"Любой текст" text, for example classB.textFieldValue = @"Любой текст" ;

Valentin Valentin 1,060 4 silver marks 6 bronze marks · Answer 2 · 2016-06-14T13:55:55

In one controller, you can save data in UserDefaults (or a similar data manager) and read it in another controller in the viewWillAppear method. So the data will be saved even between restarts of the application.

But for this you just have to tear off your hands. - Max Mikheyenko

Data transfer between controllers with saving

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