NSString always passing NULL iOS

Question

I have a quiz.vc and i am passing an NSString from on vc to another and it passes null. (i am using a UITextView)

Quiz.h
@property (nonatomic,strong) IBOutlet UITextView *textField;
@property (nonatomic, retain) NSString *userText;

Quiz.m
- (IBAction)next:(id)sender {
    // i have tried NSString *userText also and passing in userText to sfvc.string
    self.userText = self.textField.text;

            selectFriendsViewController *sfvc = [[selectFriendsViewController alloc] init];
            sfvc.string = self.userText;
}



selectFriendsViewController.h
@property (nonatomic, strong)  NSString *string;

selectFriendsViewController.m
- (void)viewDidLoad {
    [super viewDidLoad];
    NSLog(@"%@", _string);
}

its always logging null at runtime? i have tried so many ways and methods! any ideas as to how i can pass a string and not null???

Thanks

possible duplicate of [Passing Data between View Controllers](http://stackoverflow.com/questions/5210535/passing-data-between-view-controllers) — Hot Licks, Jul 28 '15 at 13:31

Leo · Answer 1 · 2015-07-28T13:35:37.180

1

Your error

  selectFriendsViewController *sfvc = [[selectFriendsViewController alloc] init];
  sfvc.string = self.userText;

This create a new instance of selectFriendsViewController,but you do not use it.It will be dealloced when the method is done.So,you got nothing.

If you fire a segue in the IBAction,use prepareForSegue to pass data.

Edit, If you fire a segue when the button clicked.

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if ([segue.destinationViewController isKindOfClass:[selectFriendsViewController class]]) {
    selectFriendsViewController * dvc = (selectFriendsViewController*)segue.destinationViewController;
    dvc.string = self.textField.text;
}
}

edited Jul 28 '15 at 13:35

answered Jul 28 '15 at 13:29

Leo

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i am new to ios development can you help me out please – Harry Jul 28 '15 at 13:30
Do you fire a segue in the method `next`? – Leo Jul 28 '15 at 13:31
i have not user the seque method to send the data before – Harry Jul 28 '15 at 13:32
thanks leo how can i put this method in the IBAction to pass it when i press the next button – Harry Jul 28 '15 at 13:39
What do you mean by "in the else condition"? – Leo Jul 28 '15 at 13:42
sorry i meant do i need to put the prepare for segue method into the IBAction – Harry Jul 28 '15 at 13:43
No,it is the method auto called by `ViewController` before fire a segue. – Leo Jul 28 '15 at 13:44
thank you very much your method worked, i have been running around and surfing the web for an answer but to no luck. you have helped me out so much. thank you very much – Harry Jul 28 '15 at 13:47

score 0 · Answer 2 · answered Jul 28 '15 at 13:58

I think u can't navigate and push the value to next viewController use this code if you using xib files.

- (IBAction)next:(id)sender {
    selectFriendsViewController *sfvc = [[selectFriendsViewController alloc] init];
    sfvc.string = self.textField.text;

[self.navigationController pushViewController:sfvc animated:YES];

}

hope that code helps you.

score 0 · Accepted Answer · answered Jul 28 '15 at 14:07

If you don't want to show null,use the below code

  #pragma mark - check string is empty or not

   - (IBAction)next:(id)sender 
    {

        self.userText = self.textField.text;
        selectFriendsViewController *sfvc = [[selectFriendsViewController alloc] init];
        sfvc.string = [self checkEmpty:self.userText];
    }

  - (void)checkEmpty:(NSString *)check
   {
     @try 
     {
       if (check.length==0)
         check = @" ";
       if([check isEqual:[NSNull null]])
         check = @" ";
     }
     @catch (NSException *exception) 
     {
       check = @" ";
     }
   }

NSString always passing NULL iOS

3 Answers3