xcode – iOS LoadPresetDemo示例代码中的AU Preset(.aupreset)

演示代码运行正常,但是当我尝试在从头开始构建的测试项目中重用.aupreset文件时,Trombone.aupreset不起作用.深入研究.我发现.aupreset文件中的音频样本路径看起来很奇怪.

plist中的路径(下图)指向：

file://localhost//Library/Audio/Sounds/Tbone/1a%23.caf

但这不是正确的路径 – 根据项目目录结构.没有“库/音频”目录 – 虚拟或真实.所以我很困惑. Apple演示工作正常,但我从头开始项目没有(尝试加载示例时得到错误-43).加载样本的代码(在底部)没有做任何事情来在运行时重新激活路径.

有谁看到我在这里误解了什么？ – 谢谢！

// Load a synthesizer preset file and apply it to the Sampler unit
- (OSStatus) loadSynthFromPresetURL: (NSURL *) presetURL {

CFDataRef propertyResourceData = 0;
Boolean status;
SInt32 errorCode = 0;
OSStatus result = noErr;

// Read from the URL and convert into a CFData chunk
status = CFURLCreateDataAndPropertiesFromResource (
            kCFAllocatorDefault,(__bridge CFURLRef) presetURL,&propertyResourceData,NULL,&errorCode
         );

NSAssert (status == YES && propertyResourceData != 0,@"Unable to create data and properties from a preset. Error code: %d '%.4s'",(int) errorCode,(const char *)&errorCode);

// Convert the data object into a property list
CFPropertyListRef presetPropertyList = 0;
CFPropertyListFormat dataFormat = 0;
CFErrorRef errorRef = 0;
presetPropertyList = CFPropertyListCreateWithData (
                        kCFAllocatorDefault,propertyResourceData,kCFPropertyListImmutable,&dataFormat,&errorRef
                    );

// Set the class info property for the Sampler unit using the property list as the value.
if (presetPropertyList != 0) {

    result = AudioUnitSetProperty(
                self.samplerUnit,kAudioUnitProperty_ClassInfo,kAudioUnitScope_Global,&presetPropertyList,sizeof(CFPropertyListRef)
            );

    CFRelease(presetPropertyList);
}

if (errorRef) CFRelease(errorRef);
CFRelease (propertyResourceData);

return result;
}