如何快速使用CFDictionarySetValue? [英] How to use CFDictionarySetValue in swift?

问题描述

当前，我正在将硬件解码Obj-C代码转换为Swift版本. (Xcode 8，Swift 3).

Currently, I am converting the hardware decoding Obj-C code to Swift version. (Xcode 8, Swift 3).

我不知道如何设置字典以在屏幕上设置输出选项，而且我也不知道如何使用它.

I don't know how to set up a dictionary to set up an output option on the screen, also, I don't know how to use it.

以下代码在Obj-C项目中正常工作:

The following code works fine in Obj-C project:

// set some values of the sample buffer's attachments
CFArrayRef attachments = CMSampleBufferGetSampleAttachmentsArray(sampleBuffer, YES);
CFMutableDictionaryRef dict = (CFMutableDictionaryRef)CFArrayGetValueAtIndex(attachments, 0);
CFDictionarySetValue(dict, kCMSampleAttachmentKey_DisplayImmediately, kCFBooleanTrue);

我尝试了以下Swift代码，但是出现了运行时错误:

I tried the following Swift code, but there was a runtime error:

// i got run-time error
let attachments = CMSampleBufferGetSampleAttachmentsArray(sampleBuffer!, true)
let dict = unsafeBitCast(attachments, to: CFMutableDictionary.self)
CFDictionarySetValue(dict, unsafeBitCast(kCMSampleAttachmentKey_DisplayImmediately, to: UnsafeRawPointer.self), unsafeBitCast(kCFBooleanTrue, to: UnsafeRawPointer.self))

将CFString转换为UnsafeRawPointer是否错误?还是使用CFDictionarySetValue方法是错误的?

Is it wrong to convert the CFString to UnsafeRawPointer? or Is it wrong to use the CFDictionarySetValue method?

这是我的错误日志.

2016-11-24 16:50:44.458 MyApp[35288:3519253] -[__NSSingleObjectArrayI __setObject:forKey:]: unrecognized selector sent to instance 0x6000002045a0
2016-11-24 16:50:44.466 MyApp[35288:3519253] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSSingleObjectArrayI __setObject:forKey:]: unrecognized selector sent to instance 0x6000002045a0'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010b02734b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010a0e421e objc_exception_throw + 48
    2   CoreFoundation                      0x000000010b096f34 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
    3   CoreFoundation                      0x000000010afacc15 ___forwarding___ + 1013
    4   CoreFoundation                      0x000000010afac798 _CF_forwarding_prep_0 + 120
    5   MyApp                             0x000000010937ac7a _TFC14MyApp16ViewerController21receivedRawVideoFramefT5frameGSaVs5UInt8_4withVs5Int32_T_ + 4890
    6   MyApp                             0x000000010937d8e2 _TFC14MyApp16ViewerController12MainCallBackfTVs5Int3212callbackCodeS1_8argumentGSqSv_7argSizeS1__T_ + 4242
    7   MyApp                             0x000000010937daed _TToFC14MyApp16ViewerController12MainCallBackfTVs5Int3212callbackCodeS1_8argumentGSqSv_7argSizeS1__T_ + 61
    8   MyApp                            0x000000010937dd56 _TTDFC14MyApp16ViewerController12MainCallBackfTVs5Int3212callbackCodeS1_8argumentGSqSv_7argSizeS1__T_ + 70
    9   MyApp                             0x000000010937dcfe _TTWC14MyApp16ViewerControllerS_18IJCallbackProtocolS_FS1_12MainCallBackfTVs5Int3212callbackCodeS2_8argumentGSqSv_7argSizeS2__T_ + 62
    10  MyApp                             0x00000001093b22b2 _TFC14MyApp11AppDelegate19MainCallBack_StreamfTVs5Int32S1_GSqSv_S1__T_ + 258
    11  MyApp                             0x00000001093d26d3 _TFZFC14MyApp19IJStreamCoreWrapper6AttachFTSv2ipSS4portSi_T_U_FTVs5Int32S1_GSqSv_S1_GSqSv__T_ + 355
    12  MyApp                             0x00000001093d2719 _TToFZFC14MyApp19IJStreamCoreWrapper6AttachFTSv2ipSS4portSi_T_U_FTVs5Int32S1_GSqSv_S1_GSqSv__T_ + 9
    13  MyApp                             0x00000001093ee176 _ZL8CallbackPN14CStreamManager9Session_TEiPvi + 70
    14  MyApp                             0x00000001093f09d3 _Z25StreamManagerThread_VideoPv + 3155
    15  libsystem_pthread.dylib             0x000000010e494aab _pthread_body + 180
    16  libsystem_pthread.dylib             0x000000010e4949f7 _pthread_body + 0
    17  libsystem_pthread.dylib             0x000000010e494221 thread_start + 13
)
libc++abi.dylib: terminating with uncaught exception of type NSException

推荐答案

在第一个代码段中，您调用了CFArrayGetValueAtIndex，该调用返回了传递给CFDictionarySetValue的字典.

In the first code snippet, you have a call to CFArrayGetValueAtIndex, which returns a dictionary that you pass to CFDictionarySetValue.

在第二个代码段中，您不会调用CFArrayGetValueAtIndex.您只需将数组传递给CFDictionarySetValue.由于数组不是字典，因此会出现致命错误.

In the second code snippet, you don't call CFArrayGetValueAtIndex. You just pass the array to CFDictionarySetValue. Since an array is not a dictionary, you get a fatal error.

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