Objective-c – make a timer count down and score displayed on the screen in Cocos2D

cocos2d-iphoneiphoneobjective c

How can I apply a timer count down in Cocos2D and the score counter that both will be display on the screen?

I am still new to this

Please help me out

Thanks a lot

Best Answer

You should have a look into the Timer class. Here is a link to the Timer class overview - cocos2d for iPhone 0.8.2. You won't need to implement one directly (but indirectly), but its good to know how it works.

For displaying the actual counter in the screen using cocos2d, have a look at LabelAtlas. Here is a link to LabelAtlas class overview - cocos2d for iPhone 0.8.2

/* basically you create a LabelAtlas subclass that
   has a method for updating itself with the current time
   or score. I will call it ScoreLabel in this example */
ScoreLabel * bonusScore = [[ScoreLabel alloc] initWithString:@"0"
                                              charMapFile:@"charMap.png"
                                              itemWidth:10
                                              itemHeight:10
                                              startCharMap:'0'];
// then schedule a method to be called that updates the current score
// schedule: paramter of type SEL. It should pass the method to be scheduled
// interval is in seconds, it determines how often the method is called.
[bonusScore schedule:@selector(updateScore) interval:0.5];

/* the implementation of the updateScore method could be */
-(void)updateScore {
    [self setString: [[World sharedWorld] timeLeft]]];
}

Have a look at the cocos2d examples for AtlasSprites (and for LabelAtlas) to see how to implement the image you need to support the class.

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Ios – How to make a UITextField move up when the keyboard is present – on starting to edit

You will only need a ScrollView if the contents you have now do not fit in the iPhone screen. (If you are adding the ScrollView as the superview of the components just to make the TextField scroll up when keyboard comes up, then it's not needed.)
The standard way to prevent the TextFields from being covered by the keyboard is to move the view up/down whenever the keyboard is shown.

Here is some sample code:

#define kOFFSET_FOR_KEYBOARD 80.0

-(void)keyboardWillShow {
    // Animate the current view out of the way
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)keyboardWillHide {
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)textFieldDidBeginEditing:(UITextField *)sender
{
    if ([sender isEqual:mailTf])
    {
        //move the main view, so that the keyboard does not hide it.
        if  (self.view.frame.origin.y >= 0)
        {
            [self setViewMovedUp:YES];
        }
    }
}

//method to move the view up/down whenever the keyboard is shown/dismissed
-(void)setViewMovedUp:(BOOL)movedUp
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3]; // if you want to slide up the view

    CGRect rect = self.view.frame;
    if (movedUp)
    {
        // 1. move the view's origin up so that the text field that will be hidden come above the keyboard 
        // 2. increase the size of the view so that the area behind the keyboard is covered up.
        rect.origin.y -= kOFFSET_FOR_KEYBOARD;
        rect.size.height += kOFFSET_FOR_KEYBOARD;
    }
    else
    {
        // revert back to the normal state.
        rect.origin.y += kOFFSET_FOR_KEYBOARD;
        rect.size.height -= kOFFSET_FOR_KEYBOARD;
    }
    self.view.frame = rect;

    [UIView commitAnimations];
}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    // register for keyboard notifications
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    // unregister for keyboard notifications while not visible.
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
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Objective-c – How to convert an NSString into an NSNumber

Use an NSNumberFormatter:

NSNumberFormatter *f = [[NSNumberFormatter alloc] init];
f.numberStyle = NSNumberFormatterDecimalStyle;
NSNumber *myNumber = [f numberFromString:@"42"];

If the string is not a valid number, then myNumber will be nil. If it is a valid number, then you now have all of the NSNumber goodness to figure out what kind of number it actually is.

Best Answer

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Objective-c – How to convert an NSString into an NSNumber

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