Ответ 1
Это может помочь вам...
- (void)maybeAutoscrollForThumb:(ThumbImageView *)thumb {
autoscrollDistance = 0;
// only autoscroll if the thumb is overlapping the thumbScrollView
if (CGRectIntersectsRect([thumb frame], [thumbScrollView bounds])) {
CGPoint touchLocation = [thumb convertPoint:[thumb touchLocation] toView:thumbScrollView];
float distanceFromLeftEdge = touchLocation.x - CGRectGetMinX([thumbScrollView bounds]);
float distanceFromRightEdge = CGRectGetMaxX([thumbScrollView bounds]) - touchLocation.x;
if (distanceFromLeftEdge < AUTOSCROLL_THRESHOLD) {
autoscrollDistance = [self autoscrollDistanceForProximityToEdge:distanceFromLeftEdge] * -1; // if scrolling left, distance is negative
} else if (distanceFromRightEdge < AUTOSCROLL_THRESHOLD) {
autoscrollDistance = [self autoscrollDistanceForProximityToEdge:distanceFromRightEdge];
}
}
// if no autoscrolling, stop and clear timer
if (autoscrollDistance == 0) {
[autoscrollTimer invalidate];
autoscrollTimer = nil;
}
// otherwise create and start timer (if we don't already have a timer going)
else if (autoscrollTimer == nil) {
autoscrollTimer = [NSTimer scheduledTimerWithTimeInterval:(1.0 / 60.0)
target:self
selector:@selector(autoscrollTimerFired:)
userInfo:thumb
repeats:YES];
}
}