cocoa touch - Resizable UILabel which scrolls across the screen

Question

Right, I'm trying to get a label with text in it (done already obviously), which scrolls across the screen.

The text that is input into the label is done by a UITextField and a UIButton. This updates fine.

But I'm trying to get the UILabel to resize accordingly to the amount of text input, so that the WHOLE lot of text scrolls across the screen.

This is the code I have at the moment for the scrolling label:

[lblMessage setText: txtEnter.text];

CABasicAnimation *scrollText;

scrollText=[CABasicAnimation animationWithKeyPath:@"position.x"];
scrollText.duration = 3.0;
scrollText.repeatCount = 10000;
scrollText.autoreverses = NO;
scrollText.fromValue = [NSNumber numberWithFloat:500];
scrollText.toValue = [NSNumber numberWithFloat:-120.0];

[[lblMessage layer] addAnimation:scrollText forKey:@"scrollTextKey"];

The problem is, sometimes is starts scrolling in the middle of the screen, and sometimes vanishes before it has fully gone acrosss.

It also cuts of text due to the label being one size.. I don't know how to change this.

Thanks in advance.

Dom

Answer 1

I believe something similar to the solution for this question would work for this case.

You could embed the UILabel in a UIScrollView, with the UIScrollView set to the max size of the label that you want to display on the screen at one time. The UIScrollView would need to have its scroll indicators turned off using its showsHorizontalScrollIndicator and showsVerticalScrollIndicator properties. On a change of text, you could do the following:

[lblMessage setText: txtEnter.text];
[lblMessage sizeToFit];
scrollView.contentSize = lblMessage.frame.size;

followed by the panning animation code as described in the above-linked question, with the frame to be panned to being the far right of the UILabel. This would cause the text to scroll at a constant rate across the label. If you want the label to scroll back to the beginning, you could use the UIView setAnimationRepeatAutoreverses: and setAnimationRepeatCount: methods in the beginning of your animation block.