Auto Scrolling UITextView Problem - iphone

Question

I am trying to auto scroll my text view and reset it to the top once it's arrived at the end.
I use this code:
-(void)scrollTextView
{
CGPoint scrollPoint = stationInfo.contentOffset;
scrollPoint = CGPointMake(scrollPoint.x, scrollPoint.y + 2);
if (scrollPoint.y == originalPoint.y + 100)
{
NSLog(#"Reset it");
scrollPoint = CGPointMake(originalPoint.x, originalPoint.y);
[stationInfo setContentOffset:scrollPoint animated:YES];
[scroller invalidate];
scroller = nil;
scroller = [NSTimer
scheduledTimerWithTimeInterval:0.1
target:self
selector:#selector(scrollTextView)
userInfo:nil
repeats:YES];
}
else
{
[stationInfo setContentOffset:scrollPoint animated:YES];
}
}
As a result, the text view jumps around wildly, but I don't quite know why. Is there maybe a better way of detecting that the text view is at the bottom? Am I setting the the scrollPoint value wrong?
Edit:
ISSUE SOLVED! I stuck to NSTimer - the missing key was calling -display for the layer.
-(void)scrollTextView
{
//incrementing the original point to get movement
originalPoint = CGPointMake(0, originalPoint.y + 2);
//getting the bottom
CGPoint bottom = CGPointMake(0, [stationInfo contentSize].height);
//comparing the two to detect a reset
if (CGPointEqualToPoint(originalPoint,bottom) == YES)
{
NSLog(#"Reset");
//killing the timer
[scroller invalidate];
scroller == nil;
//setting the reset point
CGPoint resetPoint = CGPointMake(0, 0);
//reset original point
originalPoint = CGPointMake(0, 0);
//reset the view.
[stationInfo setContentOffset:resetPoint animated:YES];
//force display
[stationInfo.layer display];
scroller = [NSTimer
scheduledTimerWithTimeInterval:0.1
target:self
selector:#selector(scrollTextView)
userInfo:nil
repeats:YES];
}
else
{
[stationInfo setContentOffset:originalPoint animated:YES];
}
}

Answer 1

You could also use CoreAnimation and animate the bounds property directly. First animate the scrolling, then in the delegate callback that the animation has finished you reset the content offset.
The callback method has to have the signature
- (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context
You could also use the new block-based methods if you are targeting iOS 4.0 and above. Then there are two blocks to be passed: in the first one you specify what to animate and in the second what to do when the animation is over.
+ (void)animateWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion
Your problem than collapses into a single line of code:
[stationInfo animateWithDuration:10.f delay:0.f options:0 animations:^{
[stationInfo setContentOffset:CGPointMake(0, [stationInfo contentSize].height)];
} completion:^(BOOL finished){
if (finished) [stationInfo setContentOffset:CGPointMake(0,0)];
}];
To be honest I am not 100% sure about the precise block syntax but this is how it should work.