目标C-通过视图控制器传递多个文本字段（或将它们转换为可变数组）以显示为标签

Question

I'm relatively new to Objective C and currently having the above issue. I've followed tutorials and tried to find the relevant topics here and I can get it to work for one variable, however I need to pass more than that between view controllers.

I'm trying to avoid using global variables, saving onto a temp file, and singleton (pattern)(?) (I hear it can get messy). I'm also trying to avoid delegating (If that's the right terminology) as I get the impression that it's becoming overcomplicated. In addition, if the below works for one, then it shouldn't be far off working for multiple.

I've explored both methods as posted in the code below. Firstly by trying to pass each text field separately, initially through one controller name, then multiple.

Secondly, by collating all the strings into a mutable array, and trying to pass this array through the controller, then splitting up this array back into strings/text for the label text. Both attempts only pass on the info for what was the active textfield after pressing the Done button.

I've played around between weak and strong properties and that hasn't made much of a difference.

The storyboard has 2 view controllers (ViewController and secondViewController), each with their own navigation controllers, and a show segue between them. ViewController has 2 text fields. secondViewController has 2 labels.

Code as follows:

ViewController.h (for both strings and array method)

#import <UIKit/UIKit.h>
#import "secondViewController.h"

@interface ViewController : UIViewController

@property (weak, nonatomic) IBOutlet UITextField *textFieldData;

@property (weak, nonatomic) IBOutlet UITextField *textFieldDataTwo;

@end

ViewController.m (first method): (Added prepareforSegue)

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

    UINavigationController *navController = (UINavigationController *)segue.destinationViewController;

    //UINavigationController *navController1 = (UINavigationController *)segue.destinationViewController;

    secondViewController *svc = (secondViewController *)navController.topViewController;
    secondViewController *svc1 = (secondViewController *)navController.topViewController;
    //Also tried navController1.topViewController with previous comment

    svc.labelText = _textFieldData.text;
    svc1.labelTwoText = _textFieldDataTwo.text;

}

secondViewController.h (for first method)

# import <UIKit/UIKit.h>

@interface secondViewController : UIViewController

@property (weak, nonatomic) IBOutlet UILabel *labelSceneTwo;
@property (weak, nonatomic) IBOutlet UILabel *labelTwoSceneTwo;

@property (weak, nonatomic) NSString *labelText;
@property (weak, nonatomic) NSString *labelTwoText;

@end

secondViewController.m (First method)

(Only added to viewDidLoad)

- (void)viewDidLoad {
    [super viewDidLoad];

    _labelSceneTwo.text = _labelText;
    _labelTwoSceneTwo.text = _labelTwoText;

}

(I'll hopefully update this post for the second method tomorrow morning).

Thank you for your time.

Update 1:

for method 2, I'm currently getting an uncaught exception of type NSException.

In ViewController.m under prepareForSegue

UINavigationController *navController = (UINavigationController *)segue.destinationViewController;

secondViewController *svc = (secondViewController *)navController.topViewController;

NSMutableArray *textFieldMArray = [NSMutableArray arrayWithObjects:_textFieldData, _textFieldDataTwo, nil];

textFieldMArray = [[NSMutableArray alloc] init];

svc.labelTextMArray = textFieldMArray;

secondViewController.h

Added:

@property (strong,nonatomic) NSMutableArray *labelTextMArray;

secondViewController.m

In view did load:

_labelTextMArray = [[NSMutableArray alloc] init];

//The line below is what is causing the termination, otherwise, screen shows 2 labels each saying "Label"
//If property of array is set to weak, then both labels appear blank.

_labelSceneTwo.text = [_labelTextMArray objectAtIndex:0];

_labelTwoSceneTwo.text = [_labelTextMArray objectAtIndex:1];

Answer 1

Final working code:
For method 2:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {  
    UINavigationController *navController = (UINavigationController *)segue.destinationViewController;
    secondViewController *controller = (secondViewController *)navController.topViewController;

    NSMutableArray *textFieldMArray = [NSMutableArray arrayWithObjects:_textFieldData.text, _textFieldDataTwo.text, nil];
    controller.labelTextMArray = textFieldMArray;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    _labelSceneTwo.text = [_labelTextMArray objectAtIndex:0];
    _labelTwoSceneTwo.text = [_labelTextMArray objectAtIndex:1];
)

For method 1:
Pretty much the same code, make sure the strings are strong as well, eg remove the weak .

How we got there
First I would suggest changing your prepareForSeque method quite a bit.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    //include the code for the navigationController
    secondViewController *destinationController = (secondViewController *)segue.destinationViewController;
    destinationController.labelText = self.textFieldData.text;
    destinationController.labelTwoText = self.textFieldDataTwo.text;
}

You should give the class a name that starts with an upper case letter like SecondViewController , that is just basic coding convention.

Regarding option 2:

NSMutableArray *textFieldMArray = [NSMutableArray arrayWithObjects:_textFieldData, _textFieldDataTwo, nil];
svc.labelTextMArray = textFieldMArray;

You should remove the line _labelTextMArray = [[NSMutableArray alloc] init]; in prepareForSegue and in viewDidLoad.

And I am not sure if navController.topViewController works the way you expect it to, I dont know if the topViewController is already updated. I would recommend getting the new viewController the way I already wrote down.