Question

我正在编写ios app，它从ip camera接收帧并用UIImage和计时器显示它们。但是我不时遇到一个难以理解的例外这是一个堆栈

thread #1: tid = 0x72198, 0x0553a240 vImage`vConvert_RGB888toBGRA8888 + 1760, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0xe429000)

frame #0: 0x0553a240 vImage`vConvert_RGB888toBGRA8888 + 1760  
frame #1: 0x05523280 vImage`vImageConvert_RGB888toBGRA8888 + 96
frame #2: 0x01f2f1aa CoreGraphics`CGSConvertBGR888toRGBA8888 + 165  
frame #3: 0x01f5a83e CoreGraphics`argb32_image + 4830
frame #4: 0x0ae007ad libRIP.A.dylib`ripl_Mark + 38  
frame #5: 0x0ae101e1 libRIP.A.dylib`RIPLayerBltImage + 1187
frame #6: 0x0adfcc59 libRIP.A.dylib`ripc_RenderImage + 258  
frame #7: 0x0adfb0cb libRIP.A.dylib`ripc_DrawImage + 1051
frame #8: 0x01fe4865 CoreGraphics`CGContextDrawImage + 435  
frame #9: 0x01657498 QuartzCore`CA::Render::(anonymous namespace)::create_image_by_rendering(CGImage*, CGColorSpace*, unsigned int) + 708
frame #10: 0x01656f31 QuartzCore`CA::Render::create_image(CGImage*, CGColorSpace*, unsigned int) + 2261  
frame #11: 0x0165784d QuartzCore`CA::Render::copy_image(CGImage*, CGColorSpace*, unsigned int, double) + 430
frame #12: 0x01738d10 QuartzCore`-[CALayer(CALayerPrivate) _copyRenderLayer:layerFlags:commitFlags:] + 557  
frame #13: 0x0173a031 QuartzCore`CA::Layer::copy_render_layer(CA::Transaction*, unsigned int, unsigned int*) + 57
frame #14: 0x0168fc9d QuartzCore`CA::Context::commit_layer(CA::Layer*, unsigned int, unsigned int, void*) + 119  
frame #15: 0x0172a727 QuartzCore`CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 317
frame #16: 0x0172a6a7 QuartzCore`CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 189  
frame #17: 0x0172a6a7 QuartzCore`CA::Layer::commit_if_needed(CA::Transaction*, void (*)(CA::Layer*, unsigned int, unsigned int, void*), void*) + 189
frame #18: 0x01690dd6 QuartzCore`CA::Context::commit_transaction(CA::Transaction*) + 1794  
frame #19: 0x01691b85 QuartzCore`CA::Transaction::commit() + 393
frame #20: 0x0174f5b0 QuartzCore`+[CATransaction flush] + 52  
frame #21: 0x021909b6 UIKit`_UIWindowUpdateVisibleContextOrder + 232
frame #22: 0x02190825 UIKit`+[UIWindow _prepareWindowsPassingTestForAppResume:] + 28  
frame #23: 0x02190a0f UIKit`+[UIWindow _prepareWindowsForAppResume] + 41
frame #24: 0x02164972 UIKit`-[UIApplication _handleApplicationResumeEvent:] + 80  
frame #25: 0x0216593f UIKit`-[UIApplication handleEvent:withNewEvent:] + 1898
frame #26: 0x02166555 UIKit`-[UIApplication sendEvent:] + 85  
frame #27: 0x02153250 UIKit`_UIApplicationHandleEvent + 683
frame #28: 0x04c6bf02 GraphicsServices`_PurpleEventCallback + 776  
frame #29: 0x04c6ba0d GraphicsServices`PurpleEventCallback + 46
frame #30: 0x0368eca5 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53  
frame #31: 0x0368e9db CoreFoundation`__CFRunLoopDoSource1 + 523
frame #32: 0x036b968c CoreFoundation`__CFRunLoopRun + 2156  
frame #33: 0x036b89d3 CoreFoundation`CFRunLoopRunSpecific + 467
frame #34: 0x036b87eb CoreFoundation`CFRunLoopRunInMode + 123  
frame #35: 0x04c6a5ee GraphicsServices`GSEventRunModal + 192
frame #36: 0x04c6a42b GraphicsServices`GSEventRun + 104  
frame #37: 0x02152f9b UIKit`UIApplicationMain + 1225
frame #38: 0x00009344 thin_client_v2`main(argc=1, argv=0xbfffee4c) + 164 at main.m:17

但是我认为这不是很有用，所以我怎么能理解我的代码中哪一行会引发异常？我添加了All Exceptions断点和this技巧，但它对我没有帮助。

由于

PS
所以我在我的项目中添加了僵尸对象。据我了解，它将帮助我获得更正确的堆栈跟踪关于创建图像。这是我的代码

- (UIImage *)imageFromAVPicture:(AVPicture)pict width:(int)width height:(int)height    
{
    CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
    CFDataRef data = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, pict.data[0], pict.linesize[0]*height,kCFAllocatorNull);
    CGDataProviderRef provider = CGDataProviderCreateWithCFData(data);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGImageRef cgImage = CGImageCreate(width, 
                                       height, 
                                       8, 
                                       24, 
                                       pict.linesize[0], 
                                       colorSpace, 
                                       bitmapInfo, 
                                       provider, 
                                       NULL, 
                                       NO, 
                                       kCGRenderingIntentDefault);
    CGColorSpaceRelease(colorSpace);
    UIImage *image = [UIImage imageWithCGImage:cgImage];

    CGImageRelease(cgImage);
    CGDataProviderRelease(provider);
    CFRelease(data);

    return image;
}

但我认为，如果问题出现在这种方法中，它会一直崩溃，对吧？但异常发生的情况非常罕见。

Answer 1

这意味着您的应用程序崩溃了，因为它触及了未映射的内存。

如果使用CGDataProviderRef创建CGImageRef（通常没有复制，然后在CGImageRef死亡之前释放像素），通常会发生这种情况。这会留下一个指向垃圾的CGImageRef，如果你试图绘制它会崩溃。如果您非常确定自己没有这样做并且可以提出可重复的样本案例，那么我建议您向Apple提交一个错误：http://bugreporter.apple.com

xcode难以理解的异常

1 个答案: