Dynamically modifying views

Question

I am implementing a custom keyboard in my app. I want the keyboard to be applicable to multiple 'types' of textFields (all numeric, but some that can have negative values vs strictly positive, some whole-numbers vs some decimal values). I want to accomplish this by hiding one or two buttons depending on the 'type' of textField.

I have built the keyboard, and can assign it as the inputView of one of my textFields (xValue). I have also written a method in my keyboard's ViewController that takes integers as inputs and should modify the keyboard buttons. At the moment, this method works in the viewDidLoad method of my ViewController, but I want to call this from the ViewController class where the keyboard is initialised. When I do try to call it, the hidden properties aren't changing.

In the viewDidLoad of the ViewController that contains my text field I have put the following:

DCKeyboard *dckvc = [[DCKeyboard alloc] initWithNibName:@"DCKeyboard" bundle:nil];
[dckvc modifyKeyboardType:0 doneNextValue:0];    // Has no effect
xValue.inputView = dckvc.view;

and in DCKeyboard.m I have defined:

@synthesize doneNextButton;
@synthesize decimalButton;
@synthesize posNegButton;

-(void) modifyKeyboardType:(int)buttonTypeNumber doneNextValue:(int)doneNextNumber {

    switch (buttonTypeNumber) {
    case 0:      // Case 0: All buttons available
        decimalButton.hidden = NO;
        posNegButton.hidden = NO;
        break;
    case 1:      // Case 1: No decimal button
        decimalButton.hidden = YES;
        posNegButton.hidden = NO;
        break;
    case 2:      // Case 2: No positive/negative button
        decimalButton.hidden = NO;
        posNegButton.hidden = YES;
        break;
    case 3:      // Case 3: No decimal or positive/negative button
        decimalButton.hidden = YES;
        posNegButton.hidden = YES;
        break;
    default:
        break;
    }

    switch (doneNextNumber) {
    case 0:      // Case 0: Done
        [doneNextButton setImage:[UIImage imageNamed:@"DoneButton.png"] forState:UIControlStateNormal];
        [doneNextButton setImage:[UIImage imageNamed:@"DoneButtonDown.png"] forState:UIControlStateHighlighted];
        break;
    case 1:      // Case 1: Next
        [doneNextButton setImage:[UIImage imageNamed:@"NextButton.png"] forState:UIControlStateNormal];
        [doneNextButton setImage:[UIImage imageNamed:@"NextButtonDown.png"] forState:UIControlStateHighlighted];
        break;
    default:
        break;
    }
}

When I try to call this as above, the

As mentioned above, if I call this from DCKeyboard's viewDidLoad method as follows, then it works - so I'm confident that I've set everything up correctly and the code works. I must just be missing a fundamental concept!

- (void)viewDidLoad {
    [super viewDidLoad];

    [self modifyKeyboardType:3 doneNextValue:1]; // This works
}

score 0 · Accepted Answer · answered Aug 21 '11 at 16:46

0

The underlying views may not be created until actually needed. In this case, that's when you access the property dckvc.view. As such, when you call your modifyKeyboardType:doneNextValue: method, none of the views actually exist to be hidden.

You could either defer this call until you're sure the views are loaded, or cache the values you pass in for the keyboard type, using them in a viewDidLoad override to update the keyboard.

answered Aug 21 '11 at 16:46

Adam Wright

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Thanks for that - simply swapping the two lines after I initialise my keyboard works. – slatfats Aug 21 '11 at 16:57

score 0 · Answer 2 · answered Aug 21 '11 at 16:51

That's simply because your IBOutlets are not pointing to anything unless the view is not loaded on the window. So if you try to modify any of there properties then nothing will happen.

This happens because your xib files is archived and none of the objects are accessible until they are presented on the screen. So you can call that method of yours in viewDidLoad which is first method that is called after the view is loaded on the screen or you can call that method after calling the methods for presenting your view on the screen like presentModalViewController:animated: or pushViewController:animated:

Thanks for the answer. I initialise my keyboard in the viewDidLoad method of the ViewController that contains the textField that will use my keyboard. The keyboard seems to be 'loaded' when assigned to be the textField's inputView - even though it's not actually displayed - so calling my method after this assignation has fixed my issue. — slatfats, Aug 21 '11 at 17:01

Dynamically modifying views

2 Answers2