ios - 拖动 UIImageView 时平移阻力？

Question

当您拖动图像时，某些应用程序具有这种“拖动阻力”。将图像从原点拖得越远，它变得越少。如何实现此功能？

Answer 1

子类化UIImageView并执行以下操作怎么样：（不完美，但可能是这样的？）

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{

    CGPoint currentPosition = [[touches anyObject] locationInView:self.superview];
    CGFloat dx = currentPosition.x  - initialCentre.x;//delta x with sign
    CGFloat dy = currentPosition.y  - initialCentre.y;//delta y with sign

    CGFloat distance = sqrt(dx*dx + dy*dy);//distance

    CGFloat weightedX = initialCentre.x +  dx * (1/log(distance)); //new x as inverse function of distance
    CGFloat weightedY = initialCentre.y +  dy * (1/log(distance)); //new y as inverse function of distance

    self.center = CGPointMake(weightedX, weightedY);//set  the center


}