ios - 未捕获的异常 : CALayer position contains NaN when doing animation

Question

当我在 iPad 上运行时，我的应用程序出现此错误:

Uncaught exception: CALayer position contains NaN

相同的代码在 iPhone 上运行良好。

- (void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views
{
    AnnotationView *aV;

    for (aV in views) {
        // Don't pin drop if annotation is user location
        if ([aV.annotation isKindOfClass:[MKUserLocation class]]) {
            continue;
        }

        // Check if current annotation is inside visible map rect, else go to next one
        MKMapPoint point =  MKMapPointForCoordinate(aV.annotation.coordinate);
        if (!MKMapRectContainsPoint(mapViewResult.visibleMapRect, point)) {
            continue;
        }

        CGRect endFrame = aV.frame;

        // Move annotation out of view
        // I checked here, CGRectEmpty returns true here

        aV.frame = CGRectMake(aV.frame.origin.x, aV.frame.origin.y - self.view.frame.size.height, aV.frame.size.width, aV.frame.size.height);

        // Animate drop
        [UIView animateWithDuration:0.5 delay:0.04*[views indexOfObject:aV] options: UIViewAnimationOptionCurveLinear animations:^{

            aV.frame = endFrame;

            // Animate squash
        }completion:^(BOOL finished){
            if (finished) {
                [UIView animateWithDuration:0.05 animations:^{
                    aV.transform = CGAffineTransformMakeScale(1.0, 0.8);

                }completion:^(BOOL finished){
                    if (finished) {
                        [UIView animateWithDuration:0.1 animations:^{
                            aV.transform = CGAffineTransformIdentity;
                        }];
                    }
                }];
            }
        }];
    }
}

我了解到，分配的帧包含 NaN 值，我使用 CGRectEmpty 函数检查了这一点并将该帧设置为 CGRectZero 但它不会工作。

我从这里得到了这个工作代码，https://stackoverflow.com/a/7045916/1603234

回溯/调试日志

*** Terminating app due to uncaught exception 'CALayerInvalidGeometry', reason: 'CALayer position contains NaN: [594.947 nan]'
*** First throw call stack:
(
    0   CoreFoundation                      0x048551e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x034ad8e5 objc_exception_throw + 44
    2   CoreFoundation                      0x04854fbb +[NSException raise:format:] + 139
    3   QuartzCore                          0x01a1be1a _ZN2CA5Layer12set_positionERKNS_4Vec2IdEEb + 190
    4   QuartzCore                          0x01a1bfd9 -[CALayer setPosition:] + 68
    5   QuartzCore                          0x01a1c6df -[CALayer setFrame:] + 799
    6   UIKit                               0x01fbbb4d -[UIView(Geometry) setFrame:] + 302
    7   MyAppName                           0x0026b025 -[ResultMapViewController mapView:didAddAnnotationViews:] + 2133
    8   MapKit                              0x01e0449b -[MKMapView annotationManager:didAddAnnotationRepresentations:] + 272
    9   MapKit                              0x01e3b53c -[MKAnnotationManager updateVisibleAnnotations] + 2052
    10  Foundation                          0x02ed6de7 __NSFireTimer + 97
    11  CoreFoundation                      0x04813ac6 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 22
    12  CoreFoundation                      0x048134ad __CFRunLoopDoTimer + 1181
    13  CoreFoundation                      0x047fb538 __CFRunLoopRun + 1816
    14  CoreFoundation                      0x047fa9d3 CFRunLoopRunSpecific + 467
    15  CoreFoundation                      0x047fa7eb CFRunLoopRunInMode + 123
    16  GraphicsServices                    0x03ccd5ee GSEventRunModal + 192
    17  GraphicsServices                    0x03ccd42b GSEventRun + 104
    18  UIKit                               0x01f60f9b UIApplicationMain + 1225
    19  MyAppName                           0x0001ba3d main + 141
    20  MyAppName                           0x000027e5 start + 53
)
libc++abi.dylib: terminating with uncaught exception of type NSException

Answer 1

我的天哪!我不知道我会犯这种“愚蠢”的错误。

是的，有问题的句子 相同的代码在 iPhone 上运行良好。 我收到错误 CALayer position contains NaN 因为在我的自定义 - (AnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id ) annotation 方法，我在这里计算

annotationView.layer.anchorPoint = CGPointMake(0.5, 1.0 - (diffFromBottom * 1.0)/annotationView.image.size.height);

annotationView.image 是空白的，因为我忘记在 iPad 项目中添加图钉图像。它存在于 iPhone 代码中。因此它被零 (0) 除并导致错误。

我放了断点，然后用 NSLog 打印就知道了，

1.0 - (diffFromBottom * 1.0)/annotationView.image.size.height 打印了这个值，-inf。这导致了应用程序崩溃。

基本上，如果您执行除以无穷大或零时会发生此错误，因此每当您遇到此类错误时，首先查看执行除法运算的代码。