错误：“二进制操作数 / 无效”

Question

我使用这段代码来移动、缩放和旋转 UIImageView。

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

    CGPoint currentTouch1;
    CGPoint currentTouch2;
    NSArray *allTouches = [touches allObjects];
    UITouch* t;
    float scale,rotation;

    if([[event allTouches] count]==1){
        t=[[[event allTouches] allObjects] objectAtIndex:0];
        if (CGRectContainsPoint([Birdie frame], [[allTouches objectAtIndex:0] locationInView:self.view]))
        { 
            touch2=[t locationInView:nil];
            Birdie.center=CGPointMake(Birdie.center.x+touch2.x-touch1.x,Birdie.center.y+touch2.y-touch1.y);
            touch1=touch2;
        }
    }
    else if([[event allTouches] count]==2)
    {
        t=[[[event allTouches] allObjects] objectAtIndex:0];
        currentTouch1=[t locationInView:nil];

        t=[[[event allTouches] allObjects] objectAtIndex:1];
        currentTouch2=[t locationInView:nil];


        scale = [self distance:currentTouch1 toPoint:currentTouch2] / [self distance:touch1 toPoint:touch2];
        rotation=atan2(currentTouch2.y-currentTouch1.y, currentTouch2.x-currentTouch1.x)-atan2(touch2.y-touch1.y,touch2.x-touch1.x);
        if(isnan(scale)){
            scale=1.0f;
        }
        NSLog(@"rotation %f",rotation);

        NSLog(@"scale %f",scale);

        if (CGRectContainsPoint([Birdie frame], [[allTouches objectAtIndex:0] locationInView:self.view]) &&
            CGRectContainsPoint([Birdie frame], [[allTouches objectAtIndex:1] locationInView:self.view]))
        {

            Birdie.transform=CGAffineTransformScale(Birdie.transform, scale,scale);
            Birdie.transform=CGAffineTransformRotate(Birdie.transform, rotation);
        }
        else // In case of scaling or rotating the background imageView
        {
            imageView.transform=CGAffineTransformScale(imageView.transform, scale,scale);
            imageView.transform=CGAffineTransformRotate(imageView.transform, rotation);
        }

        touch1=currentTouch1;
        touch2=currentTouch2;
    }
}

-(double)distance:(CGPoint)point1 toPoint:(CGPoint)point2
{
    return sqrt(fabs(point1.x - point2.x) + fabs(point1.y - point2.y));
}

但是我一直收到一个错误，二进制 / 的操作数无效。 我在下一行收到此错误：

    scale = [self distance:currentTouch1 toPoint:currentTouch2] / [self distance:touch1 toPoint:touch2];

Answer 1

您是否在 .h 文件中声明了 distance:toPoint: ？如果不是，那么编译器（严格从上到下工作，只需一次传递）不知道函数返回什么类型，并假设某些不适用于除法运算符。

因此，您很可能可以通过在 .h 文件中声明该函数或将其移到 touchesMoved:withEvent: 之前来解决问题