How to scroll characters on a label in Cocos2D? - iphone

Question

I have a sprite on which there is a label (CCLabelTTF). On that label i have A,B,C,D,E, etc printed when they are clicked. I want them to scroll left. I've googled some tuorials but i am unable to find the solution and stuck here for long. Here is the screenshot of my game. You can see the characters from A to J. When i click on more incoming characters, that portion should scroll. What can i do to make the characters scroll?
Here is the code from which the characters are shown on label (lblSelectedAlpha) added on sprite:-
-(void)showSelectedAlphaBet{
fSelectedAlphaY =26;
if (tempBackground) {
[tempBackground removeFromParentAndCleanup:YES];
}
tempBackground = [CCSprite spriteWithFile:#"stripe_2.png"];
tempBackground.position = ccp(160,30);
[self addChild:tempBackground z:30];
for (int i=0; i<[arryAddSelectedChar count]; i++) {
// NSLog(#"[arryAddSelectedChar count] %#",[arryAddSelectedChar objectAtIndex:i]);
lblSelectedAlpha = [CCLabelTTF labelWithString:
[arryAddSelectedChar objectAtIndex:i]dimensions:CGSizeMake(30,30)
alignment:UITextAlignmentCenter fontName:#"Marker Felt" fontSize:30];
lblSelectedAlpha.position = ccp(fSelectedAlphaY,25);
lblSelectedAlpha.tag=i;
lblSelectedAlpha.color = ccc3(125,125,125);
[tempBackground addChild:lblSelectedAlpha z:5];
fSelectedAlphaY +=25;
}
}

Answer 1

Scrolling is simply a constant change in position over time. Basically something like this:
-(void) update:(ccTime)delta
{
label.position = CGPointMake(label.position.x - 1, label.position.y);
}

Answer 2

Well, this is how i implemented scrolling in my cocos2d game
// How to add scroll on label. This i did with a UITextView
// inside init, i took
{
scroll = [[UIScrollView alloc] initWithFrame:CGRectMake(10,430, 150, 50)]
alphabetScroll = [[UITextView alloc] initWithFrame:CGRectMake(10,0,50 ,50)];
alphabetScroll.font = [UIFont fontWithName:#"verdana" size:30.0f];
alphabetScroll.backgroundColor = [UIColor clearColor];
alphabetScroll.textColor = [UIColor colorWithRed:125.0/255.0 green:125.0/255.0 blue:125.0/255.0 alpha:1.0f];
alphabetScroll.userInteractionEnabled=NO;
[scroll addSubview:alphabetScroll];
[[[CCDirector sharedDirector]openGLView]addSubview:scroll];
}
-(void)showSelectedAlphaBet
{
NSLog(#"showSelectedAlphaBet");
fSelectedAlphaY =26; // I have 26 alphabets
if (tempBackground) {
[tempBackground removeFromParentAndCleanup:YES];
}
// Area where alphabets are added on touch
tempBackground = [CCSprite spriteWithFile:#"stripe_2.png"];
tempBackground.position = ccp(160,30);
[self addChild:tempBackground z:30];
bottomAlphabet = #" ";
for (int i=0; i<[arryAddSelectedChar count]; i++) {
NSLog(#"[arryAddSelectedChar count] %#",[arryAddSelectedChar objectAtIndex:i]);
bottomAlphabet = [bottomAlphabet stringByAppendingString:[arryAddSelectedChar objectAtIndex:i]];
}
// Implementing shifting/scrolling
int newScrollViewWidth;
int newLabelWidth;
newScrollViewWidth =25*[arryAddSelectedChar count];
newLabelWidth =50*[arryAddSelectedChar count];
[scroll setContentSize:CGSizeMake(newScrollViewWidth, 45)];
alphabetScroll.frame = CGRectMake(0, 0, newLabelWidth, 45);
alphabetScroll.text = bottomAlphabet;
if (newScrollViewWidth > 150) {
CGPoint svos;
CGPoint pt;
svos = scroll.contentOffset;
CGRect rc = [alphabetScroll bounds];
rc = [alphabetScroll convertRect:rc toView:scroll];
pt = rc.origin;
pt.y = 0;
pt.x += 20*([arryAddSelectedChar count]-5);
[scroll setContentOffset:pt animated:YES];
}
}
// In dealloc
[alphabetScroll release];