在两个视图控制器之间执行代码/触发UI元素

Question

I'm new to objective C and design patterns like MVC, protocols and so on but this is it:

I am trying to write an iOS app within two viewcontrollers: the first has a textview where the user can write into, and the second has a UISwitch that triggers on "Value changed" and saves a file.

If I toggle by hand the switch on the SecondViewController it will save the file and that's ok.

But I wish the file could be saved from the FirstView just when the user types a specific word, it auto-switches to the second view, and auto-activates the UIswitch and all the method already behind it.

I still can't get the two interfaces working this way. Thanks everybody in advance for helping. Cheers!

---

this is connected in SecondViewController.h in the storyboard

-(IBAction)toggleFileSave:(id)sender;

and it is implemented as usual...

@interface SecondViewController ()
@property (nonatomic,weak) IBOutlet UISwitch *mySaveFileSwitch;
@end

- (void) toggleFileSave:(id)sender {
    // how do I execute this code when the user 
    // type a specific word in the first view?? 
}

Answer 1

Create a BOOL flag in your SecondViewController. Set it when the specific word is typed and push the view controller. In the viewDidLoad of SecondViewController check the flag condition.If it is set call the required method.

When the specific word is typed:

   ViewController2 *viewController = [ViewController2 alloc]init];
   viewController2.flag = YES;
   [self.navigationController pushViewController:viewController2 animated:YES];

Answer 2

In your text field delegate (add one if it doesn't exist) add this method:

- (void)textFieldDidEndEditing:(UITextField *)textField {
    /* at this point the user finished editing */
    NSString *currentText = /* read text field value */
    if ([currentText isEqualToString:/* the magic word */]) {
         /* save the file, present a view controller, etc. */
    }
}

Check UITextFieldDelegate to know the available methods, you may need more than one to get the desired behaviour.

If you want to load the second view controller in order to show the UI and the save the file you can do as サンディープ said in his or her answer:

SecondViewController *controller = [SecondViewController new]; /* init as usual */
controller.saveOnLoad = YES;

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

Then, in SecondViewController :

- (void)viewDidLoad {
    if (self.saveOnLoad) {
        /* save file in async block */
        /* set switch on */
    }
}

If you don't need to show the second view I'd move the saving functionality to its own class and use it from the first controller, showing just a confirmation message for instance.