Question

i have table cell with images, i want them to start loading, as soon as the scrolling speed drops about a threshold

however, how can i determine the current scrolling speed of a UITableView?

i found a

tableView.isDecelerating

however i want to load images, also when scrolling is slow

Answer 1

This is working for me (in the cellForRowAtIndexPath callback). I load images if the velocity falls below 1000 pixels/second:

static double prevCallTime = 0;
static double prevCallOffset = 0;

//Simple velocity calculation
double curCallTime = CACurrentMediaTime();
double timeDelta = curCallTime - prevCallTime;
double curCallOffset = self.tableView.contentOffset.y;
double offsetDelta = curCallOffset - prevCallOffset;
double velocity = fabs(offsetDelta / timeDelta);
NSLog(@"Velocity: %f", velocity);
prevCallTime = curCallTime;
prevCallOffset = curCallOffset;