惯性滚动

gistfile1.m

if (recognizer.state == UIGestureRecognizerStateEnded) {
        
        CGPoint velocity = [recognizer velocityInView:self.view];
        CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
        CGFloat slideMult = magnitude / 200;
        NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);
        
        float slideFactor = 0.1 * slideMult; // Increase for more of a slide
        CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor), 
                                         recognizer.view.center.y + (velocity.y * slideFactor));
        finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width);
        finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height);
        
        [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{
            recognizer.view.center = finalPoint;
        } completion:nil];
        
    }