Question

I want to implement a simple animation based on UIView’s center property. I have a simple view and I can drag it (UIView touchesMoved is overriden). The animation should fade slowly like the view is moved under it’s own inertia for some time after the user releases it. But for now I want simply to move the view after touch ends. Here is the code I have in touchesEnded:

int i;
    for (i=1;i<4;i++)
    {
        self.center = CGPointMake(10*i, 12*i);
        [self setNeedsDisplay];
        usleep(100000);
    }

The problem is when I run this, the code is executed nicely but “UIView” changes to late. I changed usleep time and other parameters but the result is the same. It looks like all the “pending changes” in the view are performed only after the overriden touchesEnded is finished.

Is this the right way of implementing such user interface feature or should I look for some other approaches?

Thanks in advance.

Answer 1

If you know the final positions you want your view center to have you could do this with an animation:

[UIView animateWithDuration:20
                      delay:0
                    options: UIViewAnimationOptionCurveEaseIn
                 animations:^{
                         youView.center = CGPointMake(newCenterX, newCenterY);
                       }
                       completion:^(BOOL finished){ 
                       }];