在另一个UIViewController中从UiViewController更改UILabel文本

Question

Okay it seems like I have made some mistakes and I did not get it with pointer and initializations by now...

Here is the problem :

I have a UIViewController for a registration process called : RegisterViewController

It calls a method in its ViewDidLoad :

[self performSelector:@selector(activateUsernamePopover) withObject:nil afterDelay:0.1];

This method looks like this :

- (void) activateUsernamePopover {
PopoverViewController *popcontroller = [[PopoverViewController alloc] init];

popcontroller.title = nil;

[popcontroller setPopoverText:@"Test"];

FPPopoverController *popover = [[FPPopoverController alloc] initWithViewController:popcontroller];

popover.arrowDirection = FPPopoverArrowDirectionUp;

popover.border = NO;
popover.tint = MgoGreyTint;

[popover setShadowsHidden:true];

[popover presentPopoverFromView:_usernameInput]; }

This will made a Popover visible. This works great.

But I Do have a few more TextFields where I want to show a Popover with a different text.

So I made a method in the PopoverViewController called setPopoverText :

- (void)setPopoverText:(NSString *)text {
[_popoverLabel setText:text];
[_popoverLabel setNeedsDisplay]; }

I call it in my activateUsernamePopover method :

[popcontroller setPopoverText:@"Test"];

And there is the problem.

I can log the text in the PopoverViewControllers method setPopoverText its fine.

But it did not change the text. I logged the _popoverLabel like this :

NSLog(@"%@",_popoverLabel);

and its (null).

I know there is some issue with the pointer or the instance of PopoverViewController I am working with, but objective c is not that clear to me yet.

Anyone got some answers for me ?

How can I change the Text of that UILabel ?

I also could imagine giving the Text to the Controller while instancing it.

Something like that :

PopoverViewController *popcontroller = [[PopoverViewController alloc] initWithPopoverText:@"Test"];

But I don´t know how. I don´t need to change the Text while the popover is visible. It will be released when the user taps in the TextField or elsewhere.

Thanks so far.

Answer 1

Since the UILabel is not created yet when you call init method. the way to do it is to keep text in the NSString property.

In you PopoverViewController, create the init method like this

@interface ViewController : UIViewController
- (id)initWithPopoverText:(NSString *)text;
@end

In the implementation file, keep hold of the text in the property and on viewDidLoad, you could set the text to the label.

@interface PopoverViewController ()
    @property (nonatomic) NSString *popoverText;
@end

@implement PopoverViewController
- (id)initWithPopoverText:(NSString *)text {
    self = [super init];
    if (self) {
        _popoverText = text;
    }
    return self;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    //set label.text here
    self.popoverLabel.text = self.popoverText;
}
@end