objective C enable UIScrollView scroll while UIGestureRecognizerStateChanged - iphone

Question

I added a -(void) detectTouch: (UIPanGestureRecognizer *) event for UIScrollView and detecting the angle on which user is moving his finger. My task is to scroll the UIScrollView horizontally only when user is moving the finger between 0 - 30 degrees (just to make sure he is drawing a horizontal straight line) otherwise I have to disable the UIScrollView scroll.
I am detecting the angle by drawing a triangle using the touch starting point and ending point.
Problem: I enabled the UIScrollView scroll when the angle is < 30 degrees but this is not working on the first time. Although I enabled scroll using scrollEnabled = YES it is working only when user is stopped touching the screen (taking the finger from the screen).
The following code I used to
- (void)viewDidLoad
{
[super viewDidLoad];
[self PanGesture:self.view callBack:#selector(detectTouch:) delegate:self];
incrementer = 0;
}
-(void) detectTouch: (UIPanGestureRecognizer *) event{
// Calculating point A on gesture starts
if(event.state == UIGestureRecognizerStateBegan){
pointA.x = fabs([event translationInView:event.view].x);
pointA.y = fabs([event translationInView:event.view].y);
NSLog(#"A: %f, %f", pointA.x, pointA.y);
}
incrementer += 1;
// Start calculating Point B, Point C on calling this function 3 times
if(incrementer >= 3){
// Calculating point C
pointC.x = fabs([event translationInView:event.view].x);
pointC.y = fabs([event translationInView:event.view].y);
NSLog(#"C: %f, %f", pointC.x, pointC.y);
// calculate pointB using A, C
pointB.x = fabs(pointC.x);
pointB.y = fabs(pointA.y);
NSLog(#"B: %f, %f", pointB.x, pointB.y);
float X = pointB.x - pointA.x;
float Y = pointC.y - pointB.y;
float angle = (atan(fabs(Y) / fabs(X)) * 180 / M_PI);
if(angle > 30){
// This disable is not working on while user is moving the finger
self.myScrollView.scrollEnabled = NO;
NSLog(#"UIScroll Disabled");
}else{
// This enable is not working on while user is moving the finger
self.myScrollView.scrollEnabled = YES;
NSLog(#"UIScroll Enabled");
}
incrementer = 0;
}
}
How can I enable UIScrollView scroll while user is moving the touch?

Answer 1

Since UIScrollView seems to accept scrolling only with a new touch after you set .scrollEnabled to YES, I would do the following:
set .scrollEnabled to NO
Track the touch (e. g. with touchesMoved::)
check whether you 30 degrees condition is met
use the movement to adjust UIScrollView.contentOffset