Code excerpt from Textastic's cursor navigation wheel. Shows how the move button is implemented.

gistfile1.m

- (void) awakeFromNib {
	UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGesture:)];
	[buttonMove addGestureRecognizer:panGesture];
	[panGesture release];
}

- (void) setupMoveTransform:(BOOL) move {	
	CATransform3D targetTransform = CATransform3DMakeScale(1.1f, 1.1f, 1.0f);
	targetTransform = CATransform3DTranslate(targetTransform, -6, -6, 0.0f);
	
	if (move) {
		CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
		animation.duration = 0.1f;
		animation.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];
		animation.toValue = [NSValue valueWithCATransform3D:targetTransform];
		animation.removedOnCompletion = NO;
		animation.fillMode = kCAFillModeForwards;
		[self.layer addAnimation:animation forKey:@"moveTransform"];
	} else {		
		CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
		animation.duration = 0.1f;
		animation.fromValue = [NSValue valueWithCATransform3D:targetTransform];
		animation.toValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];
		animation.removedOnCompletion = YES;
		[self.layer addAnimation:animation forKey:@"moveTransform"];
	}
}

- (IBAction) touchDownButton:(UIButton *) sender {	
	if (sender == buttonMove) {
		[self setupMoveTransform:YES];
	}
}

- (void) panGesture:(UIPanGestureRecognizer *) r {
	UIGestureRecognizerState st = r.state;
    CGPoint delta = [r translationInView:self.superview];
	
	if (st == UIGestureRecognizerStateBegan) {
		buttonMove.selected = YES;
	}
	
    // UIPanGestureRecognizer will return a delta of { -NAN, -NAN } sometimes (if it would be outside the parent view's bounds maybe?).
    if ((isfinite(delta.x) && isfinite(delta.y)) &&  (st != UIGestureRecognizerStateBegan || !(delta.x == 0 && delta.y == 0))) {
		CGRect frame = self.frame;
		frame.origin.x += delta.x;
		frame.origin.y += delta.y;
		
		[r setTranslation:CGPointZero inView:self.superview];
		
		self.frame = frame;
	}
	
	if (st == UIGestureRecognizerStateEnded) {	
		[self setupMoveTransform:NO];
		
		CGRect bounds = editorView.scrollView.superview.bounds;
		CGPoint position = [self.superview convertPoint:self.center toView:editorView.scrollView.superview];
		CGRect frame = self.frame;
		
		if (position.x + frame.size.width / 2 > bounds.size.width) {
			position.x = bounds.size.width - frame.size.width / 2;
		}
		if (position.y + frame.size.height / 2 > bounds.size.height) {
			position.y = bounds.size.height - frame.size.height / 2;
		}
		if (position.y - frame.size.height / 2 < 0) {
			position.y = frame.size.height / 2;
		}
		if (position.x - frame.size.width / 2 < 0) {
			position.x = frame.size.width / 2;
		}
		
		position = [editorView.scrollView.superview convertPoint:position toView:self.superview];

		frame.origin.x = (int)(position.x - frame.size.width / 2);
		frame.origin.y = (int)(position.y - frame.size.height / 2);
		
		[UIView beginAnimations:nil context:nil];
		self.frame = frame;
		[UIView commitAnimations];
		
		buttonMove.selected = NO;
		[editorView saveNavigationWheelPosition];
	}
}